Need some help in understanding this problem, and if there's any way to avoid it.

I notice some videos got "pressed" after using ffmpeg, even using a simple -map command.

The original video looks like this:

original video

...with the video properties (as captured by VLC):

Stream 0
   Codec: H264-MPEG-4 AVC (part 10)(avc1)
   Language: English
   Type: Video
   Video resolution: 718x478
   Buffer dimensions: 720x480
   Frame rate: 23.976215
   Decoded format:
   Orientation: Top left
   Color primaries: ITU-R BT.601 (525 lines, 60 Hz)
   Color transfer function: ITU-R BT.709
   Color space: ITU-R BT.601 Range
   Chroma location: left

Output from FFmpeg:

Stream #0:0(eng): Video: h264 (High), yuv420p(tv, smpte170m/smpte170m/bt709, progressive), 718x478 [SAR 8:9 DAR 2872:2151], SAR 223:251 DAR 80057:59989, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)

However, after using the following FFmpeg command on the video (to remove an extra subtitle):

ffmpeg -i a.mkv -map 0:v -c:v copy -map 0:a -c:a copy -map 0:2 -c:s copy a1.mkv

...the new video (a1.mkv) becomes like this:

"Squashed video"

The strange thing is that the video properties remain the same: resolution, scale, etc., (based on the VLC and FFmpeg output shown above).

Anyone know why is this and how to avoid it? Is the original video "corrupted" in the first place?

  • Share the full log of a.mkv and a1.mkv. – Gyan Mar 26 at 5:23

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