Am 23.08.21 um 07:15 schrieb Adam Nielsen via ffmpeg-user:
why is the framerate automatically changed here from 29.98 fps to 120
fps, and how can I prevent from this ?
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1280x720, 2508 kb/s, 29.98 fps, 120 tbr, 90k tbn, 2k tbc (default)
From what I can find, "tbr" is the target framerate the media is
indicating it wants.
Maybe "target buffer rate" is meant. Anyone knows?
So ffmpeg is just respecting that value.
This is not always the case. With
ffmpeg -ss 17:45 -t 0:30 -i "Original.mp4" -c copy -movflags faststart "output
0_30.mp4"
I get a tbr of 59.94.
But with
ffmpeg -t 7:30 -i "Original.mp4" -c copy -movflags faststart "output 7_30.mp4"
I get a tbr of 120.
$ ffmpeg -ss 17:45 -t 0:30 -i "Original.mp4" -c copy -movflags faststart "output
0_30.mp4"
ffmpeg version 4.4-static https://johnvansickle.com/ffmpeg/ Copyright (c)
2000-2021 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug
--disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc
--enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp
--enable-libgme --enable-gray --enable-libaom --enable-libfribidi
--enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
--enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt
--enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab
--enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264
--enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid
--enable-libzvbi --enable-libzimg
libavutil 56. 70.100 / 56. 70.100
libavcodec 58.134.100 / 58.134.100
libavformat 58. 76.100 / 58. 76.100
libavdevice 58. 13.100 / 58. 13.100
libavfilter 7.110.100 / 7.110.100
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Original.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
Duration: 02:20:49.17, start: 0.000000, bitrate: 2322 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720,
11377 kb/s, 31.54 fps, 120 tbr, 90k tbn, 2k tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp,
63 kb/s (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Output #0, mp4, to 'output 0_30.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.76.100
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720,
q=2-31, 11377 kb/s, 31.54 fps, 120 tbr, 90k tbn, 90k tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp,
63 kb/s (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mp4 @ 0x70eb080] Starting second pass: moving the moov atom to the beginning
of the file
frame= 909 fps=0.0 q=-1.0 Lsize= 9573kB time=00:00:29.99
bitrate=2614.2kbits/s speed=65.6x
video:9303kB audio:238kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 0.335273%
$ ffprobe "output 0_30.mp4"
ffprobe version 4.4-static https://johnvansickle.com/ffmpeg/ Copyright (c)
2007-2021 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug
--disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc
--enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp
--enable-libgme --enable-gray --enable-libaom --enable-libfribidi
--enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
--enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt
--enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab
--enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264
--enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid
--enable-libzvbi --enable-libzimg
libavutil 56. 70.100 / 56. 70.100
libavcodec 58.134.100 / 58.134.100
libavformat 58. 76.100 / 58. 76.100
libavdevice 58. 13.100 / 58. 13.100
libavfilter 7.110.100 / 7.110.100
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output 0_30.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.76.100
Duration: 00:00:30.04, start: 0.000000, bitrate: 2610 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720,
2536 kb/s, 29.98 fps, 59.94 tbr, 90k tbn, 2k tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp,
65 kb/s (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
$ ffmpeg -t 7:30 -i "Original.mp4" -c copy -movflags faststart "output
7_30.mp4"ffmpeg version 4.4-static https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2021
the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug
--disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc
--enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp
--enable-libgme --enable-gray --enable-libaom --enable-libfribidi
--enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
--enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt
--enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab
--enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264
--enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid
--enable-libzvbi --enable-libzimg
libavutil 56. 70.100 / 56. 70.100
libavcodec 58.134.100 / 58.134.100
libavformat 58. 76.100 / 58. 76.100
libavdevice 58. 13.100 / 58. 13.100
libavfilter 7.110.100 / 7.110.100
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Original.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
Duration: 02:20:49.17, start: 0.000000, bitrate: 2322 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720,
11377 kb/s, 31.54 fps, 120 tbr, 90k tbn, 2k tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp,
63 kb/s (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Output #0, mp4, to 'output 7_30.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.76.100
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720,
q=2-31, 11377 kb/s, 31.54 fps, 120 tbr, 90k tbn, 90k tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp,
63 kb/s (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mp4 @ 0x5909040] Starting second pass: moving the moov atom to the beginning
of the file 61x
frame=13489 fps=1393 q=-1.0 Lsize= 135974kB time=00:07:29.98
bitrate=2475.4kbits/s speed=46.5x
video:132069kB audio:3489kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 0.306792%
$ ffprobe "output 7_30.mp4"
ffprobe version 4.4-static https://johnvansickle.com/ffmpeg/ Copyright (c)
2007-2021 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug
--disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc
--enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp
--enable-libgme --enable-gray --enable-libaom --enable-libfribidi
--enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
--enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt
--enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab
--enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264
--enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid
--enable-libzvbi --enable-libzimg
libavutil 56. 70.100 / 56. 70.100
libavcodec 58.134.100 / 58.134.100
libavformat 58. 76.100 / 58. 76.100
libavdevice 58. 13.100 / 58. 13.100
libavfilter 7.110.100 / 7.110.100
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output 7_30.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.76.100
Duration: 00:07:30.01, start: 0.000000, bitrate: 2475 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720,
2404 kb/s, 29.98 fps, 120 tbr, 90k tbn, 2k tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp,
63 kb/s (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
-Ulf
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