[FFmpeg-trac] #5999(undetermined:new): Ffmpeg H264 decoder delays I-frames for some streams
FFmpeg
trac at avcodec.org
Thu Dec 8 21:18:08 EET 2016
#5999: Ffmpeg H264 decoder delays I-frames for some streams
-------------------------------------+-------------------------------------
Reporter: mont3z | Owner:
Type: enhancement | Status: new
Priority: normal | Component:
Version: unspecified | undetermined
Keywords: h264 | Resolution:
Blocking: | Blocked By:
Analyzed by developer: 0 | Reproduced by developer: 0
-------------------------------------+-------------------------------------
Comment (by mont3z):
Thx, cehoyos. Please, see attachments for a sample stream from which
frames get delayed although it only has I and P-frames. The workaround
below avoids frame delays in streams without B-frames. Some times SPS also
has num_reorder_frames != 0, so I think the configuration should precede
SPS configuration values. I'm not an expert on this but I understand that
somehow this needs to be set in decoder context.
{{{
--- a/ffmpeg-3.1.4/libavcodec/h264_ps.c Fri Nov 25 17:20:08 2016 -0800
+++ b//ffmpeg-3.1.4/libavcodec/h264_ps.c Tue Dec 06 16:48:08 2016 -0800
@@ -566,6 +566,8 @@
}
}
+ sps->num_reorder_frames = 0;
+
if (!sps->sar.den)
sps->sar.den = 1;
}}}
Result from {{{ffmpeg -i}}}:
{{{
ffmpeg -i test.h264
ffmpeg version 3.1.4 Copyright (c) 2000-2016 the FFmpeg developers
built with Microsoft (R) C/C++ Optimizing Compiler Version 18.00.40629
for x64
configuration: --arch=x86_64 --target-os=win64 --enable-ffmpeg --enable-
shared --disable-gpl --enable-encoder='mjpeg,mpeg4,pcm_mulaw' --enable-
bsfs
--enable-decoder='mjpeg,mpeg4,h264,pcm_mulaw' --enable-
filter='amix,aresample,rotate,crop,scale' --enable-muxer=mp4 --enable-
demuxer=mov --enable-pars
er=h264 --enable-protocol=file --prefix=/c/ffmpeg-3.1.4/out
--toolchain=msvc --extra-ldflags=user32
.lib
libavutil 55. 28.100 / 55. 28.100
libavcodec 57. 48.101 / 57. 48.101
libavformat 57. 41.100 / 57. 41.100
libavdevice 57. 0.101 / 57. 0.101
libavfilter 6. 47.100 / 6. 47.100
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
Input #0, h264, from 'test.h264':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: h264 (High), yuv420p, 1920x1080 [SAR 1:1 DAR
16:9], 30 fps, 30 tbr, 1200k tbn, 60 tbc
At least one output file must be specified
}}}
--
Ticket URL: <https://trac.ffmpeg.org/ticket/5999#comment:2>
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