#1664: Transcoding results in dropped frames and lowering fps
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Reporter: Barvinok | Type: defect
Status: new | Priority: normal
Component: FFmpeg | Version: git-master
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Summary of the bug:
The input video file is recorded by SonyEricsson Xperia X2 camera, has an
extension MP4 and contain "aac mp4a" and "mpeg4 (Simple Profile)"
according to ffprobe (see below).
I wanted to convert it using libx264/libvorbis as encoders and matroska as
container. The command I used was:
{{{
/opt/ffmpeg/bin/ffmpeg -i 00-00-00-00000001.mp4 \
-vcodec libx264 -crf 22 \
-acodec libvorbis -ab 64k test.mkv
}}}
The actual invocation is a bit longer, but this one is for reproducing the
effect. At first glance, ffmpeg seemed to process it all right:
{{{
ffmpeg version N-43733-ga93c221 Copyright (c) 2000-2012 the FFmpeg
developers
built on Aug 19 2012 21:27:54 with gcc 4.5.3 (Gentoo 4.5.3-r2 p1.1,
pie-0.4.7)
configuration: --prefix=/opt/ffmpeg --libdir=/usr/lib64
--shlibdir=/usr/lib64 --mandir=/usr/share/man --enable-shared --cc=x86_64
-pc-linux-gnu-gcc --cxx=x86_64-pc-linux-gnu-g++ --ar=x86_64-pc-linux-gnu-
ar --optflags='-march=native -mtune=native -O2 -pipe -mmmx -msse -msse2
-msse4a -m3dnow -fomit-frame-pointer -funroll-loops' --extra-
cflags='-march=native -mtune=native -O2 -pipe -mmmx -msse -msse2 -msse4a
-m3dnow -fomit-frame-pointer -funroll-loops' --extra-
cxxflags='-march=native -mtune=native -O2 -pipe -mmmx -msse -msse2 -msse4a
-m3dnow -fomit-frame-pointer -funroll-loops' --disable-static --enable-gpl
--enable-version3 --enable-postproc --enable-avfilter --disable-stripping
--disable-debug --disable-doc --disable-network --disable-vaapi --disable-
vdpau --disable-ffplay --enable-gnutls --enable-libmp3lame --enable-libvo-
aacenc --enable-libvo-amrwbenc --enable-libtheora --enable-libvorbis
--enable-libx264 --enable-libxvid --disable-indev=v4l --disable-indev=v4l2
--disable-indev=alsa --disable-indev=oss
libavutil 51. 70.100 / 51. 70.100
libavcodec 54. 53.100 / 54. 53.100
libavformat 54. 25.104 / 54. 25.104
libavdevice 54. 2.100 / 54. 2.100
libavfilter 3. 11.101 / 3. 11.101
libswscale 2. 1.101 / 2. 1.101
libswresample 0. 15.100 / 0. 15.100
libpostproc 52. 0.100 / 52. 0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '00-00-00-00000001.mp4':
Metadata:
major_brand : isom
minor_version : 0
compatible_brands: mp41isom
creation_time : 1980-01-17 22:55:01
Duration: 00:00:59.54, start: 0.000000, bitrate: 1168 kb/s
Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 16000 Hz, mono, s16,
23 kb/s
Metadata:
creation_time : 1980-01-17 22:55:01
handler_name : AudioHandler
Stream #0:1(eng): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D),
yuv420p, 640x480 [SAR 1:1 DAR 4:3], 1142 kb/s, 26.79 fps, 15 tbr, 1k tbn,
15 tbc
Metadata:
creation_time : 1980-01-17 22:55:01
handler_name : VideoHandler
[libx264 @ 0x1010bc0] using SAR=1/1
[libx264 @ 0x1010bc0] using cpu capabilities: MMX2 SSE2Fast FastShuffle
SSEMisalign LZCNT
[libx264 @ 0x1010bc0] profile High, level 2.2
[libx264 @ 0x1010bc0] 264 - core 120 - H.264/MPEG-4 AVC codec - Copyleft
2003-2011 - http://www.videolan.org/x264.html - options: cabac=1 ref=3
deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00
mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0
deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 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=2
keyint=250 keyint_min=15 scenecut=40 intra_refresh=0 rc_lookahead=40
rc=crf mbtree=1 crf=22.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4
ip_ratio=1.40 aq=1:1.00
Output #0, matroska, to 'test.mkv':
Metadata:
major_brand : isom
minor_version : 0
compatible_brands: mp41isom
encoder : Lavf54.25.104
Stream #0:0(eng): Video: h264, yuv420p, 640x480 [SAR 1:1 DAR 4:3],
q=-1--1, 1k tbn, 15 tbc
Metadata:
creation_time : 1980-01-17 22:55:01
handler_name : VideoHandler
Stream #0:1(eng): Audio: vorbis, 16000 Hz, mono, flt, 64 kb/s
Metadata:
creation_time : 1980-01-17 22:55:01
handler_name : AudioHandler
Stream mapping:
Stream #0:1 -> #0:0 (mpeg4 -> libx264)
Stream #0:0 -> #0:1 (aac -> libvorbis)
Press [q] to stop, [?] for help
Que input is backward in timeze= 5kB time=00:00:00.00 bitrate=
0.0kbits/s dup=0 drop=28
frame= 892 fps=9.8 q=26.0 Lsize= 7511kB time=00:00:57.91
bitrate=1062.5kbits/s dup=0 drop=703
video:7258kB audio:229kB subtitle:0 global headers:4kB muxing overhead
0.265491%
[libx264 @ 0x1010bc0] frame I:4 Avg QP:18.68 size: 21682
[libx264 @ 0x1010bc0] frame P:817 Avg QP:21.72 size: 8581
[libx264 @ 0x1010bc0] frame B:71 Avg QP:24.38 size: 4714
[libx264 @ 0x1010bc0] consecutive B-frames: 85.0% 12.3% 2.7% 0.0%
[libx264 @ 0x1010bc0] mb I I16..4: 14.3% 77.7% 8.0%
[libx264 @ 0x1010bc0] mb P I16..4: 2.5% 8.0% 0.5% P16..4: 55.0% 20.5%
9.5% 0.0% 0.0% skip: 4.1%
[libx264 @ 0x1010bc0] mb B I16..4: 0.7% 2.5% 0.1% B16..8: 42.9% 9.4%
2.0% direct:15.4% skip:26.9% L0:48.3% L1:31.7% BI:20.0%
[libx264 @ 0x1010bc0] 8x8 transform intra:73.4% inter:75.0%
[libx264 @ 0x1010bc0] coded y,uvDC,uvAC intra: 61.8% 90.1% 45.1% inter:
42.7% 68.5% 9.9%
[libx264 @ 0x1010bc0] i16 v,h,dc,p: 26% 33% 15% 25%
[libx264 @ 0x1010bc0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 19% 26% 29% 3% 4%
4% 6% 3% 5%
[libx264 @ 0x1010bc0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 29% 15% 3% 7%
6% 7% 4% 4%
[libx264 @ 0x1010bc0] i8c dc,h,v,p: 46% 28% 20% 6%
[libx264 @ 0x1010bc0] Weighted P-Frames: Y:6.2% UV:0.9%
[libx264 @ 0x1010bc0] ref P L0: 73.7% 18.0% 6.1% 2.0% 0.1%
[libx264 @ 0x1010bc0] ref B L0: 91.5% 8.2% 0.3%
[libx264 @ 0x1010bc0] ref B L1: 98.6% 1.4%
[libx264 @ 0x1010bc0] kb/s:996.45
}}}
What worried me is the discrepancy between reported fps and tbr in the
original stream, also of note was the large quantity of the dropped frames
- nearly half of them.
And indeed, while the original material had FPS of roughly 26, the
converted file displayed FPS of 15, hence the dropped frames, though I did
not specify -r option. And the difference in FPS is clearly visible by
naked eye.
Expected: I expected ffmpeg to preserve the FPS of the original material
in the absence of -r option.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1664>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker
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