[FFmpeg-user] HEVC decoding of first frame

[Christian Herglotz]

Hello,

thanks for the quick answer! I upgraded my ffmpeg to version 2.8 and 
still observe the same problem as stated before:

When timing the process I found that the decoding of the
first frame always takes twice as long as the decoding of all the other
frames.

Output of stream 1:

root at herglotz-panda:/ramcache# time -p taskset -c 0 ./ffmpeg -i 
PeopleOnStreet_intra_1frames_QP10.bin -f rawvideo -y /dev/null
ffmpeg version 2.8 Copyright (c) 2000-2015 the FFmpeg developers
   built with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
   configuration:
   libavutil      54. 31.100 / 54. 31.100
   libavcodec     56. 60.100 / 56. 60.100
   libavformat    56. 40.101 / 56. 40.101
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 40.101 /  5. 40.101
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  2.101 /  1.  2.101
Input #0, hevc, from 'PeopleOnStreet_intra_1frames_QP10.bin':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: hevc (Main), yuv420p(tv), 2560x1600, 25 tbr, 
1200k tbn, 25 tbc
Output #0, rawvideo, to '/dev/null':
   Metadata:
     encoder         : Lavf56.40.101
     Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 
2560x1600, q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc56.60.100 rawvideo
Stream mapping:
   Stream #0:0 -> #0:0 (hevc (native) -> rawvideo (native))
Press [q] to stop, [?] for help
frame=    1 fps=0.5 q=-0.0 size=    6000kB time=00:00:00.04 
bitrate=1228800.0kbiframe=    1 fps=0.5 q=-0.0 Lsize=    6000kB 
time=00:00:00.04 bitrate=1228800.0kbits/s
video:6000kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB 
muxing overhead: 0.000000%
real 4.39
user 4.28
sys 0.10


Output of stream 2:
root at herglotz-panda:/ramcache# time -p taskset -c 0 ./ffmpeg -i 
PeopleOnStreet_intra_2frames_QP10.bin -f rawvideo -y /dev/null
ffmpeg version 2.8 Copyright (c) 2000-2015 the FFmpeg developers
   built with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
   configuration:
   libavutil      54. 31.100 / 54. 31.100
   libavcodec     56. 60.100 / 56. 60.100
   libavformat    56. 40.101 / 56. 40.101
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 40.101 /  5. 40.101
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  2.101 /  1.  2.101
Input #0, hevc, from 'PeopleOnStreet_intra_2frames_QP10.bin':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: hevc (Main), yuv420p(tv), 2560x1600, 25 tbr, 
1200k tbn, 25 tbc
Output #0, rawvideo, to '/dev/null':
   Metadata:
     encoder         : Lavf56.40.101
     Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 
2560x1600, q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc56.60.100 rawvideo
Stream mapping:
   Stream #0:0 -> #0:0 (hevc (native) -> rawvideo (native))
Press [q] to stop, [?] for help
frame=    2 fps=0.9 q=-0.0 size=   12000kB time=00:00:00.08 
bitrate=1228800.0kbiframe=    2 fps=0.5 q=-0.0 size=   12000kB 
time=00:00:00.08 bitrate=1228800.0kbiframe=    2 fps=0.5 q=-0.0 Lsize=   
12000kB time=00:00:00.08 bitrate=1228800.0kbits/s
video:12000kB audio:0kB subtitle:0kB other streams:0kB global 
headers:0kB muxing overhead: 0.000000%
real 6.62
user 6.40
sys 0.21

This observation is also holds for sequences with a lower resolution.

Thanks for your help!
Christian

Am 18.09.2015 um 09:39 schrieb Moritz Barsnick:
> Hallo Christian,
>
> On Thu, Sep 17, 2015 at 10:48:16 +0200, Christian Herglotz wrote:
>> I've got a question regarding the decoding process for HEVC-coded
>> sequences. When timing the process I found that the decoding of the
>> first frame always takes twice as long as the decoding of all the other
>> frames.
> While I'm happy to try to reproduce your problem and ask smart
> questions, let me please point out:
>
>> ffmpeg version 2.1.git Copyright (c) 2000-2014 the FFmpeg developers
>>     built on Feb 20 2014 16:27:13 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
> This version of ffmpeg is extremely old, considering the amount of
> development happening. Especially with such a "new" codec as HEVC, you
> can expect many improvements over 18 months. And if ffmpeg
> happens/happened to have a bug, it may very well have been fixed in the
> meantime. Nobody here will help trying to identify a bug in such an old
> version.
>
> Please repeat your tests with a very recent version of ffmpeg, best is
> if you build if from git HEAD.
>
> Thanks,
> Gruß,
> Moritz
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> ffmpeg-user at ffmpeg.org
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-- 
Dipl.-Ing. Dipl.-Wirt.Ing. Christian Herglotz

Chair of Multimedia Communications and Signal Processing
Friedrich-Alexander University Erlangen-Nürnberg
Cauerstr. 7, D-91058 Erlangen, Germany