[FFmpeg-user] Growing file processing

[Bouke / VideoToolShed]

Bouke

www.VideoToolShed.com
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> On 26 Feb 2019, at 13:20, Moritz Barsnick <barsnick at gmx.net> wrote:
> 
> On Tue, Feb 26, 2019 at 11:00:40 +0100, g.cemeli at woody-technologies.com wrote:
>> 2 - Growing file generation slower than processing
>> ffmpeg.exe -i input.mxf growing.mkv
>> ffmpeg.exe -i growing.mkv -c copy output.mkv
>>> ffmpeg stops when it reaches the current end of the growing file.
>> 
>> Any way to avoid this behavior ?
> 
> My second recommendation with "tail" here works for me:
> https://lists.ffmpeg.org/pipermail/ffmpeg-user/2016-July/032874.html <https://lists.ffmpeg.org/pipermail/ffmpeg-user/2016-July/032874.html>

Hi Moritz,

Great trick, works here too, except that it of course never stops.
So, it’s either telling FFmpeg how long the file ‘should’ be, or do a 'pkill tail'.
Is there a more sophisticated way?

Next, it is dog slow, sorta kinda defeating the whole idea.
(Since the data is piped at a speed that FFmpeg will never be able to catch up with the original…)

bouke$ ffmpeg -i /Users/bouke/Desktop/Judith/Harding.mxf  -an -s 120x40 -t 15  -y  /Users/bouke/Desktop/Judith/test.mp4
Stream #0:0 -> #0:0 (mpeg2video (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
frame=  375 fps=136 q=2.0 Lsize=     365kB time=00:00:15.00 bitrate= 199.6kbits/s    
video:363kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.674411%

vs
bouke$ tail -c +1 -F /Users/bouke/Desktop/Judith/Harding.mxf  | ffmpeg -i - -an -s 120x40 -t 15  -y  /Users/bouke/Desktop/Judith/test.mp4
  Stream #0:0 -> #0:0 (mpeg2video (native) -> mpeg4 (native))
frame=  375 fps= 28 q=2.0 Lsize=     365kB time=00:00:15.00 bitrate= 199.5kbits/s dup=1 drop=0    
video:363kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.674757%

Am I missing something?

Bouke

> Moritz
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