[FFmpeg-user] Growing file processing

[Marton Balint]

On Sat, 2 Mar 2019, Bouke / VideoToolShed wrote:

>
> Bouke
>
> www.VideoToolShed.com
> van Oldenbarneveltstraat 33
> 6512 AS  Nijmegen
> +31 6 21817248
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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%
>

Another approach is to use -rw_timeout 1000000 and -follow 1 options. 
Stangely the 'follow' option is documented under the ftp protocol when it 
in fact applies to the file protocol...

Regards,
Marton