FFmpeg concat problem

Question

I just want to add black video at the beginning of the video

I have found following commands.

ffmpeg -i s1.mp4 -f lavfi -i color=c=black -t 10 -filter_complex "[1:v][0:v]scale2ref=1*iw/1/sar:ih/1[wm][base];[base][wm]concat=2" output.mp4

MainQuestion:

How can I solve this issue?

Gyan · Accepted Answer · 2018-10-31 10:52:09Z

1

concat requires videos to have the same sample aspect ratio as well as the same resolution.

So, in this case,

ffmpeg -i s1.mp4 -f lavfi -i color=c=black -t 10 -filter_complex "[1:v][0:v]scale2ref[wm][base];[wm]setsar=1[wm];[base][wm]concat=2" output.mp4

or

ffmpeg -i s1.mp4 -f lavfi -i color=c=black -t 10 -filter_complex "[1:v][0:v]scale2ref[wm][base];[base][wm]concat=2:unsafe=1" output.mp4

answered Oct 31 '18 at 10:52

Gyan

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I carried out above command, and the terminal was stuck。 @Gyan – gs z Oct 31 '18 at 14:59
Run command with -report added and share report. Kill ffmpeg after a minute if it doesn't exit. – Gyan Oct 31 '18 at 15:20
I found a error: [Parsed_concat_1 @ 0x7f9d74e086c0] Input link in1:v0 parameters (size 212x160, SAR 160:159) do not match the corresponding output link in0:v0 parameters (212x160, SAR 1:1) – gs z Oct 31 '18 at 15:26
Use the 2nd command. – Gyan Oct 31 '18 at 15:48

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