I have obtained a video, ffprobe for it shows:
$ ffprobe test-000000.mp4
ffprobe version 4.2.7-0ubuntu0.1 Copyright (c) 2007-2022 the FFmpeg developers
...
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test-000000.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.29.100
Duration: 00:01:25.76, start: 0.040000, bitrate: 187 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 608x448, 186 kb/s, 8.98 fps, 25 tbr, 12800 tbn, 50 tbc (default)
Metadata:
handler_name : VideoHandler
mediainfo for the same shows:
$ mediainfo test-000000.mp4
General
Complete name : test-000000.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 1.92 MiB
Duration : 1 min 25 s
Overall bit rate : 187 kb/s
Writing application : Lavf58.29.100
Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3
Format settings : CABAC / 4 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 4 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 1 min 25 s
Bit rate : 186 kb/s
Width : 608 pixels
Height : 448 pixels
Display aspect ratio : 4:3
Frame rate mode : Variable
Frame rate : 8.979 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.076
Stream size : 1.90 MiB (99%)
Writing library : x264 core 155 r2917 0a84d98
Encoding settings : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x3:0x3 / me=dia / subme=1 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=25 / keyint_min=2 / scenecut=40 / intra_refresh=0 / rc=crf / mbtree=0 / crf=35.0 / qcomp=0.00 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / pb_ratio=1.30 / aq=1:1.00
Codec configuration box : avcC
When I start playing this video with vlc, it starts playing fine for 5-6 seconds, and then I get suddenly:
...
[00007f066cc1bad0] avcodec decoder error: more than 5 seconds of late video -> dropping frame (computer too slow ?)
[00007f066cc1bad0] avcodec decoder error: more than 5 seconds of late video -> dropping frame (computer too slow ?)
[00007f066cc1bad0] avcodec decoder error: more than 5 seconds of late video -> dropping frame (computer too slow ?)
[00007f066cc1bad0] avcodec decoder error: more than 5 seconds of late video -> dropping frame (computer too slow ?)
[00007f066cc1bad0] avcodec decoder error: more than 5 seconds of late video -> dropping frame (computer too slow ?)
...
I think also, the video at that point was showing a still frame for quite a long time (screen capture from a PC desktop), so it's quite possible the capturing process did not insert keyframes there or something.
So, I was wondering, is it possible to fix this kind of an error message without reencoding (in ffmpeg that would be -vcodec copy), aside from inserting keyframes if that is necessary (though I'm not sure, maybe inserting keyframes does count like re-encoding in greater extent than -vcodec copy?)? If not, what would be the best way to fix this problem with ffmpeg, so I end up with minimal changes in existing quality?
