Hi Doug,
I have been able to confirm on my end that when I run ffmpeg with -threads 0, I
also see a lag in audio/video sync. This I had not noticed before, but looks
like an ffmpeg bug (?). I tried again specify threads (-threads 2, -thread 3)
and maybe did not see quite as bad a lag (but perhaps just a little…) Have you
tried specifying a set number of threads?
Cheers,
Brian
On Jul 24, 2012, at 4:27 PM, Hall, Douglas wrote:
> Hi Brian!
>
> I would say the video is about 500-1000 milliseconds behind the audio.
> Definitely noticeable. The one test I did was with a 45 minute H.264/MP4
> encoded video coming from an Ncast box. I am running the following ffmpeg
> command line to crop out the presenter portion of the video:
>
> ffmpeg -strict unofficial -i #{in.video.path} -r 30 -vcodec libx264 -b 1024k
> -ab 96000 -ar 22050 -vf crop=640:360:0:0 -threads 0
> #{out.dir}/#{out.name}#{out.suffix}
>
> Note there is no sync issue when running this ffmpeg command without the
> –threads option.
>
> Best regards,
>
> - Doug
>
> From: Brian O'Hagan <[email protected]>
> Reply-To: Matterhorn Users <[email protected]>
> Date: Tuesday, July 24, 2012 4:11 PM
> To: Matterhorn Users <[email protected]>
> Subject: Re: [Matterhorn-users] ffmpeg multithreaded
>
> Hi Doug! Just curious; How much of an audio drift are you seeing with
> -threads 0? And, are you seeing drift on short or long-form videos? Last,
> which audio / video codecs are being used for the encoding?
>
> --
> Brian O'Hagan
>
> On Tuesday, July 24, 2012 at 3:56 PM, Hall, Douglas wrote:
>
>> Hi,
>>
>> What are your latest experiences with using ffmpeg multithreaded? Running a
>> quick test with –threads 0 seems to introduce some audio/video sync issues.
>> I haven't tried tweaking other options much yet, just wondering what others
>> may know…
>>
>> Thanks,
>>
>> - Doug
>> _______________________________________________
>> Matterhorn-users mailing list
>> [email protected]
>> http://lists.opencastproject.org/mailman/listinfo/matterhorn-users
>
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