[Cin] Segmented Recording from input stream

Fri May 30 15:27:16 CEST 2025

пт, 30 мая 2025 г., 15:55 Terje J. Hanssen <terjejhanssen at gmail.com>:

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> Den 30.05.2025 00:15, skrev Andrew Randrianasulu:
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> пт, 30 мая 2025 г., 00:30 Andrew Randrianasulu <randrianasulu at gmail.com>:
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>>
>>
>> чт, 29 мая 2025 г., 23:42 Terje J. Hanssen via Cin <
>> cin at lists.cinelerra-gg.org>:
>>
>>> Is it possible with CinGG's Record utility (via FFMPEG) to record a
>>> stream to file segments of same duration or file size and use auto-naming?
>>>
>>> Typical example:
>>> Record a video/audio input stream (i.e from playing a camcorder tape
>>> cassette) and encode to output file segments of 10 minutes or 10 GB each
>>> and auto-name file numbers.
>>>
>>> Similar example code using an input file instead at
>>>
>>> https://unix.stackexchange.com/questions/1670/how-can-i-use-ffmpeg-to-split-mpeg-video-into-10-minute-chunks
>>>
>>> Just use what is built into ffmpeg to do exactly this.
>>>
>>> ffmpeg -i invid.mp4 -threads 3 \
>>>        -vcodec copy *-f segment -segment_time 10:00 \
>>>        -reset_timestamps 1 \
>>>        cam_out_h264_%02d.mp4*
>>>
>>> This will split it into roughly 10-minute chunks, split at the relevant
>>> keyframes, and will output to the files *cam_out_h264_01.mp4,
>>> cam_out_h264_02.mp4*, etc.
>>>
>> Very interesting question! Never tried this, did not even know it existed!
>>
>> As long as this -f just ordinary avformat muxer you probably can copy
>> your favourite ffmpeg video/audio profiles with new .seg name and put
>> "segmented" at very first line there , where "mov" or "matroska" or other
>> format name was, and add rest of options. And add pattern (%02d) into name
>> just as with ffmpeg-based image lists.
>>
>> I'll try this with termux's version, but I do not have audio here so it
>> will be incomplete.
>>
>
> so I created this file:
>
> cat ffmpeg/video/mpeg2.seg
> segment mpeg2video
> segment_format=mpeg
> segment_time=00:10
> reset_timestamps=1
> trellis=2
> mbd=rd
> cmp=2
> subcmp=2
> b=4000000
>
>
> and it worked! in sense it created six segments, each with corresponding
> increasing timecode. But they all uneven duration, probably due to mpeg2
> codec placing keyframes at will.
>
> You can try to modify it back to 10:00 segment time and see how it work
> for longer encode?
>
>
> As I'm not sure if and how you applied your file above with regards to
> Cingg Record,
>

just put file where other video profiles live? (ffmpeg/video folder of your
cingg installation)

What worries me is audio. If segmented audio muxer cut it differently from
video we will get desync.

May be setting labels at specific intervals and then using "write new file
at label" checkbox is better idea?

I simply did a test with my system's ffmpeg segment muxer:
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> https://ffmpeg.org/ffmpeg-formats.html#segment_002c-stream_005fsegment_002c-ssegment
>
> Input file: hdv09_04_h264.mp4
>   Duration: 00:03:58.88, start: 0.000000, bitrate: 8963 kb/s
>
> Tried 1 minute segment time:
>
> ffmpeg -hide_banner -i hdv09_04_h264.mp4 -threads 3 \
>        -vcodec copy -f segment -segment_time 01:00 \
>        -reset_timestamps 1 \
>        cam_out_h264_%02d.mp4
>
> [segment @ 0x563c2874fa80] Opening 'cam_out_h264_01.mp4' for
> writingeed=52.1x
> [segment @ 0x563c2874fa80] Opening 'cam_out_h264_02.mp4' for
> writingeed=55.5x
> [segment @ 0x563c2874fa80] Opening 'cam_out_h264_03.mp4' for writingeed=
> 57x
> [out#0/segment @ 0x563c28727680] video:257421KiB audio:3749KiB
> subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead:
> unknown
> frame= 5972 fps=1445 q=-1.0 Lsize=N/A time=00:03:58.80 bitrate=N/A
> speed=57.8x
> [aac @ 0x563c28721a40] Qavg: 454.522
>
> 68M    cam_out_h264_00.mp4
> 63M    cam_out_h264_01.mp4
> 59M    cam_out_h264_02.mp4
> 68M    cam_out_h264_03.mp4
> --------
>
>   Duration: 00:01:00.38, start: 0.058000, bitrate: 9394 kb/s
>   Duration: 00:01:00.00, start: 0.000000, bitrate: 8672 kb/s
>   Duration: 00:01:00.60, start: 0.000000, bitrate: 8104 kb/s
>   Duration: 00:00:57.93, start: 0.000000, bitrate: 9705 kb/s
>
> In total:     00:03:58.93  which is 00:00:00.03 (=3/100 sek) more than the
> input file
> which I think is good enough for practical purposes (editing and
> backup/preservation/archival)
>
> I wonder if it is within or out of our reach to make some targeted
> profiles for backup/preservation?
> I.e would it be of interest and possible to utilize/integrate/use oss
> tools and scripts as found here:
> https://avpres.net/Bash_AVpres/
> https://avpres.net/FFmpeg/im_FFV1.html
>

Up to interested party, I guess.

>
> The programs dvgrab and possibly the newer vrecord can also autosplit by
> scenes
> https://linux.die.net/man/1/dvgrab
> https://github.com/amiaopensource/vrecord
> https://github.com/mipops/dvrescue
>

Yes, I was thinking about this, but unfortunately without any testable
idea. Sorry.

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