[mythtv-users] cut HD-PVR content with audio/video sync issues

Greg Oliver oliver.greg at gmail.com
Fri Feb 19 11:39:13 UTC 2010


On Fri, Feb 19, 2010 at 2:07 AM, Nick Rout <nick.rout at gmail.com> wrote:
> On Fri, Feb 19, 2010 at 4:49 PM, Greg Oliver <oliver.greg at gmail.com> wrote:
>> On Thu, Feb 18, 2010 at 9:42 PM, Nick Rout <nick.rout at gmail.com> wrote:
>>> On Fri, Feb 19, 2010 at 12:16 PM, Doug Vaughan <r.d.vaughan at rogers.com> wrote:
>>>> I have not tried Robert's script in a very, very long time. The only reason
>>>> is that I do not trust the automated process to decide where the cuts should
>>>> be and you cannot adjust the edits in a Avidemux project file at least with
>>>> v2.4.x this may have changed in v2.5.x.
>>>>
>>>> As for Avidemux v2.5.x, just last week I tried Ubuntu's v2.5.1 deb, a v2.5.2
>>>> deb and compiled 2.5.2 version from the Avidemux svn. All aborted trying to
>>>> open a HDPVR mpg/AC3 recording. I posted the abort on the Avidemux forum but
>>>> did not get a response. I would like to upgrade but right now I am sticking
>>>> to my compiled version from late last November.
>>>>
>>>> I used to sometimes get audio out of sync. If the out of sync was consistent
>>>> throughout the file I used mkvmerge GUI to make adjustments. Out of sync
>>>> audio that happened somewhere after the beginning of the loss-less video was
>>>> usually a reflection of some transmission error recorded on the original
>>>> HDPVR mpg file.
>>>>
>>>> When I first got my HDPVR I could not channel change my STB so I recorded on
>>>> a STB/PVR before using the HDPVR. Every time I had an HDPVR recoding issue I
>>>> could trace it back to the source. One movie I recorded multiple times from
>>>> my Cable company and it always had the same picture and sound errors in the
>>>> same time locations.
>>>>
>>>> Over the last 12 months or so there has been both firm ware upgrades but
>>>> also a number of improvements on the Linux side (driver and MythTV). So I
>>>> rarely see audio out of sync any more.
>>>>
>>>> I may give Roberts script another shot and adjust the commercial cuts within
>>>> MythTV itself. I just had gotten very used to the manual process.
>>>>
>>>> I thought I read that your audio goes out of sync gradually. If true then
>>>> try an experiment.
>>>> 1) Use the script's avidemux project file but change the output container to
>>>> be avi rather than mkv
>>>> 2) Then process the resulting avi file through ffmpeg or mkvmerge to see if
>>>> the final mkv file maintains audio sync.
>>>
>>> I read a thread on the mythbuntu forum during this week that was about
>>> hdpvr audio sync. Here is what was written in conclusion:
>>>
>>> "The audio delay actually gets worse as time goes on. At the
>>> beginning, it seems ok and then after a few minutes, you start to
>>> notice a change...or drift. So, using that key word, I searched around
>>> and found some people were also referring to this as "drift". Using
>>> the right word makes all the difference in your searching.
>>>
>>> People were noticing that the video was recording at 60fps rather than
>>> 59.94 (like the audio). Sure enough, so was mine. Using MediaInfo, I
>>> was able to easily confirm this.
>>>
>>> I had installed the most recent driver/firmware (in windows).
>>> Hauppauge calls it a driver, but it is actually both. This was
>>> supposed to fix the problem, but obviously had not. I called Hauppauge
>>> to inquire about it. I asked if there was a way to confirm that the
>>> firmware actually "took". They said no. How dumb is that? So, I
>>> re-installed the firmware/driver in windows. It said that everything
>>> went fine. I put it back on my Myth box and it still had the same
>>> problem.
>>>
>>> Next, I hunted down an old driver/firmware and installed that. Blammo,
>>> it worked. My videos were 59.94fps! I went back (just for giggles) and
>>> re-installed (for the 3rd time) the newest firmware/driver and it
>>> continued to record videos at 59.94fps.
>>>
>>> So, either the new firmware simply won't take on my unit and I'm on
>>> the old firmware....or putting an old firmware on the box and then
>>> trying the new firmware again worked...?
>>>
>>> But, there is NO WAY to tell what firmware you have on the box. Dumb dumb dumb.
>>>
>>> I do know that older firmware can be a little problematic. The box can
>>> freeze up and Linux can even sometimes loose the device...i.e. you
>>> need to unplug the USB and plug it back in.
>>>
>>> So far, I have not had that problem, so I suspect that the new
>>> firmware did take."
>>
>> Loading the hdpvr module logs the firmware version.  Easiest to grab
>> it from dmesg..
>
>
> Right, good to know, my point was that the firmware version makes a
> diference between 60fps and 59.94 fps, and that difference is related
> to audio sync problems (well so the poster in that thread says
> anyway).

Yep, that got me wondering about mine since I have rarely used it so
far, so I set up for all night recordings.  Woke up this morning, and
it is completely dead  :-/

Time to find out how good Hauppauge's rma dept is I guess!


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