[FFmpeg-user] R: Generete one second of black video and relative silence audio with the same duration

[Gian Maria Allibrante]

Thanks Moritz, sorry for the confusion, may ask:

  *   How to remove this audio packet? (i need this trick to concatenate videos with total duration multiple of the GOP destined to infinite mpeg dash pseudo live loop, mp4box will fail after some cycles with this duration dicrepance, it's unable to skip it)
  *   How you see this information: side_data_type=Skip Samples etc.

Gian

________________________________
Da: ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> per conto di Moritz Barsnick <barsnick at gmx.net>
Inviato: sabato 25 gennaio 2020 22:53
A: FFmpeg user discussions <ffmpeg-user at ffmpeg.org>
Oggetto: Re: [FFmpeg-user] Generete one second of black video and relative silence audio with the same duration

On Sat, Jan 25, 2020 at 22:26:31 +0000, Gian Maria Allibrante wrote:
> Hi Moritz, thanks for reply, this one, im always unable to get round match duration:
>
> echo VIDEO FORMAT CONTAINER DURATION:
> ffprobe -v error -show_entries format=duration \
>   -of default=noprint_wrappers=1:nokey=1 output.mp4
> echo VIDEO STREAM DURATION:
> ffprobe -v error -select_streams v:0 -show_entries stream=duration \
>   -of default=noprint_wrappers=1:nokey=1 output.mp4

Ah, I think I understand now. You are trying to get the same duration
from the container as from the video stream.

Honestly, I was looking for a totally different problem:

> > VIDEO FORMAT CONTAINER DURATION: 3.026000
> > VIDEO STREAM DURATION: 3.000000

You showed us *three* seconds results, not one second. This totally
distracted from your actual issue! ;-)

Regarding the approx 0.026 extra seconds:
For some reason, ffmpeg creates an additional initial audio packet,
marked with
side_data_type=Skip Samples
skip_samples=1105

If those initial samples are skipped, the total length is exactly okay.
I'm not sure whether ffmpeg does this due to restrictions regaring the
audio packet size.

Moritz
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