Difference between revisions of "XvMC"

From MythTV Official Wiki
Jump to: navigation, search
(Obtaining XvMC capable drivers for your chipset: Fixed ATI_Proprietary_Driver link)
m (remove categories)
(10 intermediate revisions by 5 users not shown)
Line 1: Line 1:
 +
{{Warning box|XvMC has been deemed unnecessary for playback of any content it supports, and detrimental to future graphical enhancements to MythTV.  It has been removed from MythTV as of 0.25, and superseded by [[VDPAU]], [[VAAPI]], and [[Broadcom_Crystal_HD|Crystal HD]].}}
 
{{Wikipedia}}
 
{{Wikipedia}}
{{HelpUs}}
 
  
 
== Introduction ==
 
== Introduction ==
Line 29: Line 29:
 
| nvidia
 
| nvidia
 
! style="background-color: lightgreen" | Yes
 
! style="background-color: lightgreen" | Yes
| Any recent version of the driver is acceptable.  See the Nvidia page for more details. Be careful though: some nVidia cards do not support XvMC: the only cards that support XvMC are those that support nVidia "PureVideo", which is not the case for most motherboard GPUs such as the [http://www.nvidia.com/object/mcp_intel_page.html GeForce 7 series]. Geforce 8 and later do not support XvMC: driver limitation.<br><br>
+
| Any recent version of the driver is acceptable.  See the Nvidia page for more details. Be careful though: some nVidia cards do not support XvMC: the only cards that support XvMC are those that support nVidia "PureVideo", which is not the case for most motherboard GPUs such as the [http://www.nvidia.com/object/mcp_intel_page.html GeForce 7 series]. Geforce 8 and later do not support XvMC. This is a hardware and driver limitation. Use VDPAU instead. The latest NVidia driver packages support XvMC on hardware which supports XvMC instead of VDPAU.<br><br>
 
''"The 173.14.09 release includes support for the XVideo Motion Compensation (XvMC) version 1.0 API on GeForce 5 series, GeForce 6 series and GeForce 7 series addin cards, as well as motherboard chipsets with integrated graphics that have PureVideo support."'' [http://us.download.nvidia.com/XFree86/Linux-x86/173.14.09/README/appendix-g.html]
 
''"The 173.14.09 release includes support for the XVideo Motion Compensation (XvMC) version 1.0 API on GeForce 5 series, GeForce 6 series and GeForce 7 series addin cards, as well as motherboard chipsets with integrated graphics that have PureVideo support."'' [http://us.download.nvidia.com/XFree86/Linux-x86/173.14.09/README/appendix-g.html]
 
| [http://www.nvidia.com www.nvidia.com]
 
| [http://www.nvidia.com www.nvidia.com]
Line 171: Line 171:
  
 
Run ldconfig one last time, to tell the kernel about the new driver.
 
Run ldconfig one last time, to tell the kernel about the new driver.
 
*************************************************************************
 
 
  
 
The easy answer to getting XvMC working on an Intel chipset is to upgrade your installation to Fedora 12, Ubuntu 9.10 or the equivalent which have everything already built. You can download the driver tarball from  http://xorg.freedesktop.org/archive/individual/driver/ and if necessary, the server from ...individual/xserver, and use those. They require compilation but rarely give problems. Using the git sources ranks much lower compared to the other options.
 
The easy answer to getting XvMC working on an Intel chipset is to upgrade your installation to Fedora 12, Ubuntu 9.10 or the equivalent which have everything already built. You can download the driver tarball from  http://xorg.freedesktop.org/archive/individual/driver/ and if necessary, the server from ...individual/xserver, and use those. They require compilation but rarely give problems. Using the git sources ranks much lower compared to the other options.
Line 567: Line 564:
 
** Plus automatic interlace/progressive source detection
 
** Plus automatic interlace/progressive source detection
 
* Bitstream processing (CAVLC/CABAC)
 
* Bitstream processing (CAVLC/CABAC)
 
== Alternatives ==
 
There are alternative methods for hardware assisted [[MPEG-2]] playback of standard definition video:
 
*[[Hauppauge PVR-350]]
 
 
  
 
== External Links ==
 
== External Links ==
Line 578: Line 570:
 
*[http://www.freedesktop.org/wiki/Software/vaapi New Video Acceleration API at freedesktop.org]
 
*[http://www.freedesktop.org/wiki/Software/vaapi New Video Acceleration API at freedesktop.org]
  
[[Category:Glossary]] [[Category:HOWTO]] [[Category:Hardware]] [[Category:Video display cards]]
+
[[Category:Glossary]] [[Category:Outdated]]

Revision as of 17:23, 18 January 2011

Warning.png Warning: XvMC has been deemed unnecessary for playback of any content it supports, and detrimental to future graphical enhancements to MythTV. It has been removed from MythTV as of 0.25, and superseded by VDPAU, VAAPI, and Crystal HD.

Wikipedia-logo-en.png
Wikipedia has an article on:

Introduction

( Current as of May 1, 2008)

X-Video Motion Compensation, or XvMC, is a standardized API in The X Window System which allows video programs to offload motion compensation and iDCT (Inverse Discrete Cosine Transform) portions of MPEG-2 decoding to the GPU hardware, through the use of XvMC enabled drivers. XvMC can greatly reduce CPU utilization when playing back MPEG-2 video. In theory it should also reduce bus bandwidth requirements. Savings will be most dramatic with slow CPUs or when playing HDTV. SDTV will benefit as well, but most modern CPUs can already play back SDTV without XvMC. MythTV can be compiled to use XvMC for native playback. External players such as Xine and Mplayer can also be compiled to support XvMC.


Currently, only MPEG-2 is supported. This is usually a hardware limitation, but can also in some chips case be a device driver limitation. As an exception, one of the newer VIA Unichrome chips is capable of XvMC accelerated MPEG-4 playback, but it is not supported by the official UniChrome driver at the time of writing this, instead you have to turn to the openChrome project drivers (which has an updated forked version of libxvmc).

A new video acceleration API is being developed, in an effort lead by Intel. This new API supports more complete offload (VLD) as well as iDCT+MC, and can support acceleration of MPEG-4 ASP (H.263), MPEG-4 AVC (H.264), VC-1/VMW3, as well as MPEG-2. The website for this effort is located at: http://www.freedesktop.org/wiki/Software/vaapi. XvMC-vld is also available on Via Unichrome-Pro chipsets, through the openchrome driver.

Some users have also provided a chart of example CPU savings

Drivers

Each hardware video card capable of XvMC video acceleration requires a software driver to enable these features. Below is a list of the recommended software drivers and driver versions for each supported hardware type.

Chipset Driver XvMC? Version Source
NVIDIA nvidia Yes Any recent version of the driver is acceptable. See the Nvidia page for more details. Be careful though: some nVidia cards do not support XvMC: the only cards that support XvMC are those that support nVidia "PureVideo", which is not the case for most motherboard GPUs such as the GeForce 7 series. Geforce 8 and later do not support XvMC. This is a hardware and driver limitation. Use VDPAU instead. The latest NVidia driver packages support XvMC on hardware which supports XvMC instead of VDPAU.

"The 173.14.09 release includes support for the XVideo Motion Compensation (XvMC) version 1.0 API on GeForce 5 series, GeForce 6 series and GeForce 7 series addin cards, as well as motherboard chipsets with integrated graphics that have PureVideo support." [1]

www.nvidia.com
NVIDIA nv No Included version Included with Xorg distribution
Unichrome openchrome Yes Included version Included in Xorg 6.9 and above distributions.
Intel i810 or intel Yes Included version Included in Xorg distribution
ATI
N/A No At this time, there is no XvMC support for ATI cards in Linux drivers N/A
S3 Chrome
s3g Yes MPEG-2 HW acceleration (only support Red Hat Enterprise Linux WS release 4) on some Chrome 20 GPUs made by S3 company s3graphics.com

Obtaining XvMC capable drivers for your chipset

Available drivers

In order for MythTV to utilize the XvMC feature of your video chipset, you need to install the appropriate XvMC-enabled driver for your distribution. Drivers are presently available for NVidia, Via Unichrome and Intel video chipsets. There are presently (May, 2008) no XvMC enabledd ATI drivers. ATI has been releasing upgraded drivers for Radeon 8500 or so chipsets and as of November 2008, version 8.10 appears to have an unannounced XvMC capability. See the wiki here and ATI's site here.

The installation process will vary by chipset and distribution but some general recommendations can be made. There are main three steps: installing the driver (including compiling in some cases), revising xorg.conf and XvMCConfig to enable XvMC, and, finally, setting the playback profile in Mythtv (see the Playback_profiles page.

XvMCW libraries

For many distributions, a separate XvMCW (Wrapper) library package can be installed. This is the library that MythTV will use to hook into the XvMC support in the driver. It provides a common interface for applications wishing to use XvMC.

 yum install libXvMCW

or the equivalent will do the trick. This may already be installed by your distribution.

NVIDIA Chipsets

For NVIDIA chipsets, the open source nv driver is provided in all distributions. The nv driver does not enable XvMC. NVidia provides a closed source binary driver installer package on their website which gives an XvMC enabled driver. Clicking on the 'Archive' link, below the first listed driver will disclose not only the older "legacy" drivers, but also other more recent drivers. Download and follow the instructions there for executing the package and installing the modules.

In Fedora

The ATRPMS site packages nvidia drivers for installation on new Fedora distributions and the RPMFusion site has packages for some older distributions as well as newer.

In Ubuntu

The Envy project provides binary packages for Ubuntu and Debian to quickly install and configure nvidia drivers and XvMC support. It also will install the binary ATI drivers which do not, however, support XvMC.

VIA Unichrome Chipsets

For via unichrome chipsets, go to Openchrome.org to download the source code or for links to binary driver packages. Note that not all features of the unichrome chipsets, especially TV-out, are presently working, but XvMC appears to be working on all chipsets using video-out (VGA/DVI).

This thread throws some light on many issues people have been facing with recent distributions; MythDora5 works out of the box with Via SP13000 MB which has a CN400 chipset however MythBuntu 810 & 904 do not work. A patch has been provided in this thread which may be of help to Intrepid 8.10 users - http://ubuntuforums.org/showpost.php?p=6269306&postcount=14. There are similar patches from the same provider for various other distributions.

Intel Chipsets

(Revised January 1, 2010)

Intel chipsets are often considered 'low-powered' but in fact the drivers have been deficient in enabling the capabilities of the hardware. XvMC has had a chequered history. As of May 1, 2008, the intel driver which was included in most distributions did NOT enable XvMC, except on i810 and i815 chipsets. XvMC was then made available through the xf86-video-intel driver as of version 2.3.0 on all Intel chipsets. XvMC capability was later disabled in the 2.6.0 and subsequent driver versions due to problems.

XVMC has now been re-enabled in driver version 2.9.0 for all chipsets. A frame size limitation of 720x576 pixel frames was also removed so that XvMC is available for 1920x1080 frame sizes.

Ubuntu 9.04 (Jaunty) and Fedora 11 as distributed, has XvMC disabled. Driver version 2.9.0 was released September 29, 2009 and has been included in Ubuntu Karmic (9.10) and Fedora 12 together with the required X server version 1.6. XvMC can be enabled with the correct options in xorg.conf.

The latest driver version is available as a source tar from:

 http://xorg.freedesktop.org/archive/individual/driver/

or through git from

 $ git-clone git://anongit.freedesktop.org/git/xorg/driver/xf86-video-intel 

Compiling/Installing the driver

NVIDIA

The nvidia installer binary runs from runlevel 3. Edit the first uncommented line in /etc/inittab to read:

 id:3:initdefault: 

and reboot. (Reverse the edit after the installation). The installer binary will install the driver in /usr/lib/xorg/modules/drivers and the accompanying libraries in /usr/lib.

NOTE: DO not attempt to use the experimental vdpau drivers (180 series). The vdpau driver setup installs non-standard header files in addition to the driver files. Other chipsets will fail to operate if the non-standard headers are installed. The installation is not reversed by the uninstall script provided. It is also not clear whether non-vdpau capable nvidia hardware will operate properly with the vdpau enabled driver. Possibly but without xvmc.

VIA Unichrome

To get the latest code using anonymous subversion, cd to a scratch space and use:

 svn co http://svn.openchrome.org/svn/trunk openchrome 

'cd' into the newly created openchrome sub-directory, and do the 'configure && make && make install' cycle. The openchrome.org website has some good documentation. The openchrome users list is a good resource as well.

Intel

Requirements for Compilation:

(seriously revised January 1, 2010)

Since driver version 2.9.0 or 2.9.1 is now available in mainstream repositories there is no real need to compile from source. The following is retained for reference purposes only.

Note: if you obtain the driver and the xserver tars from http://xorg.freedesktop.org/archive/individual/ a 'configure --prefix=/usr' && make && make install' on the xserver as root should suffice to build the driver.

The Driver Source is available at:

   http://xorg.freedesktop.org/archive/individual/driver/xf86-video-intel-2.9.1.tar.bz2 

or get the driver source by running:

   $ git-clone git://anongit.freedesktop.org/git/xorg/driver/xf86-video-intel 

Unpack the tarball (if required) and 'cd' into the xf86-video-intel directory which has been created. If you downloaded the tarball, run ./configure --prefix=/usr.

If you downloaded with git, run './autogen.sh' Autogen.sh creates and then runs 'configure'


Compile Time:

By default configure wants to build (and install) in /usr/local/, but we want everything in /usr so that xorg works as usual. So re-run configure as follows, whichever version you are building.

$ ./configure --prefix=/usr
$ make
$ sudo make install

The 'make install' step will install the intel_drv.so driver in /usr/lib/xorg/modules/drivers and the libIntelXvMC.so.1.0.0 library in /usr/lib. The libI810XvMC.so driver will be installed in the same place or may be replaced by a symlink to the libIntelXvMC library.

Check that the driver was put into the correct place. If you are unsure, check in /usr/local/lib/xorg/modules/drivers. If the new driver is there, you forgot to (re-)run configure with --prefix=/usr since it should be in /usr/lib/xorg/modules/drivers/

Check that (or revise as necessary to put) '/usr/lib/xorg/modules/drivers' and '/usr/lib/xorg/extensions are listed in /etc/ld.so.conf.

Run ldconfig one last time, to tell the kernel about the new driver.

The easy answer to getting XvMC working on an Intel chipset is to upgrade your installation to Fedora 12, Ubuntu 9.10 or the equivalent which have everything already built. You can download the driver tarball from http://xorg.freedesktop.org/archive/individual/driver/ and if necessary, the server from ...individual/xserver, and use those. They require compilation but rarely give problems. Using the git sources ranks much lower compared to the other options.

Configuring xorg.conf

Each chipset driver has specific configuration options to enable XvMC.

NVIDIA

Appendix B to the Nvidia Driver README details the available xorg.conf switches.

Use the 'nvidia-settings' or 'nvidia-config' control panel program to disable Video Texture Adapter and/or Video Blitter Adapter "Sync to VBlank" checkboxes (on the "X Server XVideo Settings" page)

Revise /etc/X11/xorg.conf, modifying the Device Section to add 3 Options. The resulting section may look something like this:

 Section "Device"
      Identifier "Videocard0"
      Driver  "nvidia"
      Option "UseEvents" "true"
      Option "XvmcUsesTextures" "false"  # necessary for color Chromakey OSD)
      Option "NVAGP" "1"                 # some users report 2 or 3 works better
 EndSection

Note that since driver version 100.14.11 there is a bug for users of AGP cards in the nvidia driver that requires the NVAGP option set to 0 (turning off agpgart support). See this nvidia forums post for more info.

The following option appears to be required for XvMC use with nvidia chipsets, especially when using the Chromakey OSD. This turns off the 'Compiz eye-candy'. (The 'Extensions' option is a part of xorg.conf, and is a replacement for SubSections which were used to pass Options to a specific module. Since modules are now 'automagically' loaded through extmod, the "Modules" section has disappeared. The 'Extensions' section is the replacement for that capability.)

 Section "Extensions"
      Option "Composite" "Disabled"
 EndSection

Enabling the UseEvents option can sometimes bring out an issue with the nvidia driver resulting in a blue line around the screen. To fix this simply run the following somewhere during your Xorg startup:

xvattr -a XV_COLORKEY -v 66048

Refer to this section on the Nvidia proprietary driver page for more information.

VIA Unichrome

Many Via based motherboards and especially the EPIA motherboards have video *and* TV outputs. The TV output can be sent directly to a standard NTSC or PAL (CRT-style) TV. These motherboards have a setting in the BIOS which must be set to enable the dual outputs. In addition, the dual outputs must be enabled in xorg.conf. XvMC is enabled by default on chipsets which support it, but depends upon certain extensions, especially 'dri'. Revise xorg.conf as follows:

Section "Module"
        Load  "dbe"
        Load  "extmod"
        Load  "fbdevhw"
        Load  "glx"
        Load  "record"
        Load  "freetype"
        Load  "type1"
        Load  "dri"
EndSection

Section "Extensions"
        Option                  "Composite"             "Enable"
EndSection

Section "Device"
        Identifier              "CardTV"
        Driver                  "via"
        VendorName              "VIA"               # Optional
        BoardName   "VIA Technologies, Inc. S3 Unichrome Pro VGA Adapter"
        Option      "Active Device"   "CRT TV"
        Option      "TVType"          "NTSC"
        Option      "TVOutput"        "S-Video"
        Option      "EnableAGPDMA"    "1"
EndSection

Section "DRI"
        Group                          "video"
        Mode                            0666
EndSection

INTEL

The 'intel' man page which should be installed with the driver contains a full listing of the switches now available. Revise /etc/X11/xorg.conf as follows:

Section "Device"
        Identifier      "Videocard0"
        Driver          "intel"
        Option          "XvMCSurfaces" "7"      # for i810/i815 chipsets only, otherwise
                                                # XvMC is disabled
        Option          "XvMC"  "true"          # enable XvMC chipsets after i815 
                                                # default is disabled
        Option          "UseEvents" "true"
## The following 2 options should be used together, and may or may not make a difference to CPU load
        Option          "AccelMethod" "UXA"     # "XAA and "EXA" have been removed from the latest driver
        Option          "CacheLines" "xxxx"     # Allows the user to change the amount of graphics
                                                # memory used for 2D acceleration and video when
                                                # XAA acceleration is  enabled.
                                                # Decreasing leaves  more  for 3D textures. Increasing
                                                # can improve 2D performance at the expense of 3D.
                                                # xxxx=8192/16384/32768 etc.
        # Note AccelMethod XAA does not appear to work with Xvmc enabled. Testing required. 
EndSection

Note that the intel driver, like the latest nvidia driver loads all the required extensions by default and does not require a 'Module' section in xorg.conf. The Intel linux graphics page states that xorg.conf requires

 Section "DRI"
           Mode 0666
      EndSection 

Due to the fact that all extensions are loaded by default, without a "Modules" section, this Section is not required (DRI is enabled without it), but it actually may do something....

Enabling the chipset library

Each chipset provides an interface between the XvMC library and the actual driver. This is usually handled by what is called the XvMCW wrapper library. The XVMCW library looks to a text configuration file in order to find the correct XvMC library. XvMC will not be enabled if the XvMCConfig file refers to the XvMCW library. The wrapper configuration file is found at /etc/X11/XvMCConfig and you either may have to create this file yourself as it is sometimes not pre-installed even though it is needed, or edit it to remove the libXvMCW.so reference and replace it with the proper reference.

This file contains a single line consisting of the driver library name:

NVIDIA

libXvMCNVIDIA_dynamic.so.1

unichrome

libXvMCVIA.so or libXvMCVIAPro.so (depending on the chipset)

intel

/usr/lib/libIntelXvMC.so

Note that the Intel driver requires the absolute pathname of the library. If you used a package (atrpms, livna) based driver installation, you might also be able to find the library name by doing

 rpm -ql <driver-package> | grep -i xvmc

and look for library names that include the XvMC text.

Checking your installation

You will have to reboot. To check if XvMC is properly enabled, run:

$ cat /var/log/Xorg.0.log | grep Motion 

and you should see:

(II) Loading extension XVideo-MotionCompensation


If you try: cat /var/log/Xorg.0.log | grep -i XvMC your driver might also report loading the options such as:

(**) NVIDIA(0): Option "XvMCUsesTextures" "True"

with VIA SP13000 this will be:

(II) CHROME(0): [XvMC] Registering chromeXvMCPro.
(II) CHROME(0): [XvMC] Initialized XvMC extension.

Success!

If you are having problems, or are just unsure whether your setup is correct, you can compile this small program and run it. If it will not build, then you probably do not have the pre-requisites and no wonder your xvmc will not work! I do not know who gave this program to me, but Michal Podsiadlik <michal (et) gov.one.pl and Ken Harris deserve the credit for writing it.

/*
 ** XvMC extension info program
 **
 ** author:
 ** Michal Podsiadlik <michal (et) gov.one.pl>
 ** Ken Harris : fixed some bugs with the "chroma" and "codec" fields, 2005-10-01
 **
 ** compile using this command (I hope ;-))
 ** gcc -o xvmcinfo xvmcinfo.c -lXvMCW
 * */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <X11/Xlib.h>
#include <X11/extensions/XvMClib.h>

void usage(char *c)
{
    fprintf(stderr, "usage:\n" "%s [-display displayname]\n", c);
    exit(1);
}

int main(int argc, char **argv)
{
    Display *xserver;
    int iscreen;
    char *display = NULL;

    if (argc != 1 && argc != 3)
        usage(argv[0]);

    if (argc == 3) {
        if (!strcmp(argv[1], "-display"))
            display = argv[2];
        else
            usage(argv[0]);
    }

    xserver = XOpenDisplay(display);
    if (!xserver) {
        fprintf(stderr, "failed to connect to display: %s\n", display);
        return 1;
    }

    {
        unsigned int xv_major, xv_minor, x, y, z;
        if (XvQueryExtension(xserver, &xv_major, &xv_minor, &x, &y, &z) !=
            Success) {
            fprintf(stderr, "no Xv extension available\n");
            XCloseDisplay(xserver);
            return 1;
        }
        printf("\n" "Xv version %i.%i\n", xv_major, xv_minor);
   }

    {
        int xvmc_major, xvmc_minor;
        if (XvMCQueryVersion(xserver, &xvmc_major, &xvmc_minor) != Success) {
            fprintf(stderr, "no XvMC extension available\n");
            XCloseDisplay(xserver);
            return 1;
        }

        printf("XvMC version %i.%i\n\n", xvmc_major, xvmc_minor);
    }

    for (iscreen = 0; iscreen < ScreenCount(xserver); iscreen++) {
        unsigned int iadapt, num_adaptors;
        XvAdaptorInfo *adaptor_info;

        printf("screen number %i\n", iscreen);

        XvQueryAdaptors(xserver, RootWindow(xserver, iscreen),
                        &num_adaptors, &adaptor_info);

        if (!num_adaptors) {
            printf("   no Xv adaptors found\n");
            continue;
        }

        for (iadapt = 0; iadapt < num_adaptors; iadapt++) {
            int isurf, num_surfaces;
            XvMCSurfaceInfo *xvmc_info;

            printf("   info for adaptor %i [%s]\n", iadapt,
                   adaptor_info[iadapt].name);

            xvmc_info =
                XvMCListSurfaceTypes(xserver, adaptor_info[iadapt].base_id,
                                     &num_surfaces);

            printf("      number of XvMC surface types: %i\n\n",
                   num_surfaces);

            for (isurf = 0; isurf < num_surfaces; isurf++) {
                static char *codec[] = { "", "MPEG1", "MPEG2", "H263", "MPEG4" };       // XXXX HACK
                static char *chroma[] = { "", "XVMC_CHROMA_FORMAT_420 ", "XVMC_CHROMA_FORMAT_422 ", "XVMC_CHROMA_FORMAT_444 " };        // XXXX HACK
                printf("      info about surface %i:\n"
                       "         max_width=%i\n"
                       "         max_height=%i\n"
                       "         subpicture_max_width=%i\n"
                       "         subpicture_max_height=%i\n"
                       "         chroma_format:\n"
                       "            %s\n"
                       "         mc_type:\n"
                       "            format                   : %s\n"
                       "            accelaration start from  : %s\n"
                       "         flags:\n"
                       "            %s%s%s%s\n\n",
                       isurf,
                       xvmc_info[isurf].max_width,
                       xvmc_info[isurf].max_height,
                       xvmc_info[isurf].subpicture_max_width,
                       xvmc_info[isurf].subpicture_max_height,
                       /* chroma_format */
                       chroma[xvmc_info[isurf].chroma_format & 0xf],
                       /* mc_type */
                       codec[xvmc_info[isurf].mc_type & 0xf],
                       xvmc_info[isurf].mc_type & XVMC_IDCT ? "IDCT " : "MOCOMP ",
                       /* flags */
                       xvmc_info[isurf].flags & XVMC_OVERLAID_SURFACE ?  "XVMC_OVERLAID_SURFACE " : "",
                       xvmc_info[isurf].flags & XVMC_BACKEND_SUBPICTURE ?  "XVMC_BACKEND_SUBPICTURE " : "",
                       xvmc_info[isurf].flags & XVMC_SUBPICTURE_INDEPENDENT_SCALING ?  "XVMC_SUBPICTURE_INDEPENDENT_SCALING " : "",
                       xvmc_info[isurf].flags & XVMC_INTRA_UNSIGNED ? "XVMC_INTRA_UNSIGNED " : "");
               }
            XFree(xvmc_info);
        }
        XvFreeAdaptorInfo(adaptor_info);
  }
  XCloseDisplay(xserver);
  return 0;
}

MythTV XvMC Support

Packages and Distributions

Most package and distributions of MythTV should have XvMC enabled by default. You can check your version by doing

mythfrontend --version

and looking for

Options compiled in:
linux release using_oss using_alsa using_jack using_backend using_dbox2 using_dvb using_firewire using_frontend    
using_hdhomerun using_iptv using_ivtv using_joystick_menu using_lirc using_v4l using_x11 using_xrandr 
using_xv using_xvmc using_xvmcw using_xvmc_vld using_bindings_perl using_bindings_python using_opengl
using_ffmpeg_threads using_libavc_5_3 using_live

If you see options like using_xvmc and using_xvmcw then your Myth system is prepared for XvMC.

Compiling from source

When you run configure, if you have the proper XvMC development files installed (libXvMC-devel, libXvMCW-devel) , you should see this type of output from the configure script:

# Video Output Support
x11 support               yes
xrandr support            yes
xv support                yes
XvMC support              yes
XvMC VLD support          yes
XvMC pro support          yes
XvMC OpenGL sup.          no
XvMC libs                 -lXvMCW

The last libs line will tell you which libraries that MythTV is compiling against. In this case, it is the XvMC wrapper mentioned above. For some, it may be the nvidia libraries. But regardless, you need to see yes before building MythTV.

If installing MythTV on Gentoo Linux, make sure video card is properly configured in /etc/make.conf to include, "i810", "nvidia" or "via". The "xvmc" USE flag is also required. These flags can usually be set on a per package basis in /etc/portage/package.use, for example:

$ cat /etc/portage/package.use
media-tv/mythtv xvmc

Or globally for all packages in /etc/make.conf via USE="xvmc"

Configuring MythTV

Important.png Note: When running mythfrontend for the first time to test XvMC, try running it from a command window so you can see the output from mythfrontend. If mythfrontend cannot load the XvMC library, you will see a line in the logs about this when starting playback and you will see log entries about xvmc not being available

XvMC usage is controlled using the Playback profiles feature of MythTV as of version 0.21. In previous versions, you simply set the Preferred MPEG-2 Decoder to one of the XvMC methods appropriate for your chipset. With 0.21, this is a more flexible configuration allowing for different decoders depending on the content. For XvMC, the Bob deinterlacer provides the best deinterlacing but with some performance penalty.

Warning.png Warning: Do not configure your Playback profile for more than one CPU when using XvMC. This will crash the frontend when attempting to playback recordings.

Sometimes the OpenGL VSync feature can affect XvMC use and performance. This can be enabled or disabled in the frontend configuration if compiled into your MythTV system.


OSD

softblend

If your on screen display is greyscale, then XvMC is working and you are using the softblend OSD. If you are experiencing performance issues related to the OSD (on screen display), disabling the OSD fade will improve this greatly. You can also try using the Chromakey OSD

Chromakey

The chromakey OSD will provide a color OSD and for many chipsets, this also uses far less CPU resources, making playback smoother.


Important.png Note: Chromakey OSD is not supported on newer Nvidia cards of the 6000 series and above

Using other applications

If you use other applications for playback in MythVideo such as mplayer or xine, each has its own configuration options for using XvMC

MPlayer

MPlayer includes an XvMC output plugin. To use it, try this:

mplayer -vo xvmc -vc ffmpeg12mc

(assuming you are running mplayer with XvMC support compiled in)

  • Note - unichrome support in mplayer requires a patch.

Xine

Xine's has two plugins for XvMC support, the first is named xvmc as you would expect, however to take advantage of XvMC acceleration on nVidia graphics cards using the nVidia binary drivers they have a seperate plugin named xxmc (xx instead of xv).

To use Xine with XvMC support for most graphics cards use:

xine -V xvmc 

To use Xine with XvMC support for nVidia graphics cards use:

xine -V xxmc 

(assuming, of course, that xine has been compiled with XvMC support.)

Hardware acceleration processes not yet supported by XvMC

XvMC does have the potential for more than it currently features it supports today. Modern graphic processors (since the DirectX 9 generation and newer) support more than just accelerating motion compensation and iDCT, and they can support more video formats than only MPEG-2 as XvMC does today. NVIDIA's PureVideo Technology and ATI's AVIVO Technology support hardware accelerated video decoding for MPEG-2, MPEG-4 AVC (H.264), and WMV3 (often referred to as WMV9 because Microsoft released it as the same time as Windows Media Player 9). Unfortunate, neither NVIDIA or ATI have yet to open up those technologies to Linux nor the API documentations to the open source community, and no publicly known attempt to reverse engineer access to those APIs have been made.

As a temporary (or permanent) solution to this, shaders in and/or Cg code could be written for these processes and added to the XvMC library to gain some of the additional advantages that GPU assisted video decoding brings and Shader Model 3.0 based GPUs can support today. (Best would be if FFmpeg was used as a reference codec and player/utility). Both NVIDIA and ATI have extensive tools for creating and maintaining the process of developing shaders easier than it has been in the past.

Processes that can be accelerated for most video formats

  • Motion compensation (mo comp)
  • Inverse Discrete Cosine Transform (iDCT)
    • Inverse Telecine 3:2 and 2:2 pull-down correction
  • Inverse modified discrete cosine transform (iMDCT)
  • in-loop deblocking
  • intra-frame prediction
  • inverse quantization (IQ)
  • Variable Length Decoding (VLD)
    • More commonly known as slice level acceleration
  • Spatial-Temporal De-Interlacing
    • Plus automatic interlace/progressive source detection
  • Bitstream processing (CAVLC/CABAC)

External Links