[mythtv-users] transcoding hdtv video to mpeg4 Keeping ac3 5.1

[James Blake]

I am using the MythTv built-in transcoder, it creates
a nuv file, here is example of playing the file with
mplayer:

jblake at localhost /media/tvrecord $ mplayer
1311_20070506210100.nuv -ac hwac3
MPlayer dev-SVN-rUNKNOWN-3.4.5 (C) 2000-2007 MPlayer
Team
CPU: AMD Athlon(tm) 64 Processor 3700+ (Family: 15,
Model: 4, Stepping: 10)
3DNowExt supported but disabled
CPUflags:  MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 0 SSE: 1
SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 3DNow
SSE SSE2
Can't open joystick device /dev/input/js0: Permission
denied
Can't init input joystick

Playing 1311_20070506210100.nuv.
NuppelVideo file format detected.
[VO_TDFXVID] Can't open /dev/tdfx_vid: No such file or
directory.
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec
codec family
Selected video codec: [ffodivx] vfm: ffmpeg (FFmpeg
MPEG-4)
==========================================================================
==========================================================================
Forced audio codec: hwac3
Cannot find codec for audio format 0x1.
Read DOCS/HTML/en/codecs.html!
Audio: no sound
Starting playback...
Compiler did not align stack variables. Libavcodec has
been miscompiled
and may be very slow or crash. This is not a bug in
libavcodec,
but in the compiler. Do not report crashes to FFmpeg
developers.
VDec: vo config request - 960 x 544 (preferred
colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.76:1 - prescaling to correct movie
aspect.
VO: [xv] 960x544 => 960x544 Planar YV12
V:   0.7  15/ 15 ??% ??% ??,?% 0 0

MPlayer interrupted by signal 2 in module: sleep_timer


Does the MythTv transcoder save ac3 5.1 sound when
converting to this format, if so, how does it play
back?


--- Matt Mossholder <matt at mossholder.com> wrote:

> On Sat, 2007-05-12 at 18:04 -0700, James Blake
> wrote:
> > Hi,
> > 
> > I am trying to transcode my 1080i hdtv content to
> > mpeg4, it compresses great: Here are the transcode
> > settings that I am using:
> > _ lossless transcoding
> > x Resize video while transcoding
> > Width: 960 Height: 544
> > Codec Mpeg-4
> > bitrate: 2400, max qual: 2 min qual: 15, max qual
> b/t
> > frames: 3
> > _ scale bitrate for framesize
> > x enable high-quality encoding
> > x enable 4mv encoding
> > x enable interlaced DCT encoding
> > x enable interlaced motion estimator
> > Code: Uncompressed
> > sampling rate: 48000
> > volume 90%
> > 
> > but when trying to playback the ac3 audio appears
> to
> > be missing.
> > 
> > when playing with mplayer, forcing ac3 audio, I
> get
> > this:
> > Forced audio codec: hwac3
> > Cannot find codec for audio format 0x1.
> > Read DOCS/HTML/en/codecs.html!
> > Audio: no sound
> > Starting playback.
> > 
> > Before, transcode, it definitely had the ac3
> sound..
> > 
> > Is there a way to keep the ac3 audio track????
> > 
> > I have tried it a couple ways, but it appears to
> lose
> > it no matter what. I need to have my 5.1 surround
> > sound.
> > 
> > Thanks in advance!!!!!
> > Jamie
> > 
> 
> Jamie,
> 	If you are using an MP4 container (file extension
> is .mp4), then you
> won't be able to store AC3 audio in the file in a
> way that most players
> will understand. The MP4 container format currently
> only supports MPEG
> standards for audio and video, as well as PCM. So
> you will need to
> either do MPEG2,3 or 4 audio to remain in spec for
> that container
> format. 
> 
> 	If you are using AVI, MKV or any of the others,
> then I have no idea, I
> would think it would work :)
> 
> 
> 		--Matt
> 
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> 





       
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