CODEWITHSUNDEEP
ffmpegterminal
user3310334
user3310334

Reputation:

ffmpeg concat filter is dropping first second of second video

con.txt

file one.mp4
file two.mp4

The command

ffmpeg -f concat -safe 0 -i con.txt out.mp4

produces a video that doesn't contain the first second of two.mp4.

ffprobe two.mp4

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'two.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
  Duration: 00:00:15.20, start: 0.000000, bitrate: 1644 kb/s
  Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 428x640, 1644 kb/s, 10 fps, 10 tbr, 10240 tbn, 20 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]

I get an interesting error attempting another concatenation method (neither video has audio btw)

ffmpeg -i one.mp4 -i two.mp4 -filter_complex "[0:v] [1:v] concat=n=2:v=1:a=0 [v]" -map "[v]" out.mp4

Input link in0:v0 parameters (size 428x640, SAR 0:1) do not match the corresponding output link in0:v0 parameters (428x640, SAR 1576:1575)

How can I join these two videos together sequentially without losing any frames from either?

Upvotes: 0

Views: 315

Answers (1)

kesh
kesh

Reputation: 5463

The concat filter expects the streams to be concatenated to have the identical properties (size, sample aspect ratio (SAR), pix_fmt, etc.). The error message is saying that SARs are not matching up. You can insert setsar filters upstream of concat filter to resolve this. Assuming these videos have square pixels (1576:1575 is pretty darn close to 1:1), we can do this:

ffmpeg -i one.mp4 -i two.mp4 \
  -filter_complex "[0:v]setsar=1:1[L0]; \
                   [1:v]setsar=1:1,fps=30[L1]; \
                   [L0][L1]concat=n=2:v=1:a=0 [v] " \
  -map "[v]" out.mp4

If you get other errors, you need to prepend more filters to condition your streams to match each other.

Edit: Added fps filter to the second video (10 fps) to match the first (30 fps)

Upvotes: 1

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