Re: [Matterhorn-users] ffmpeg multithreaded

Tue, 24 Jul 2012 13:27:30 -0700

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
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