[FFmpeg-user] Let ffmpeg pick correct fps from stdin

Tue Jan 19 09:40:08 CET 2016

On 15/01/2016 16:33, Jean-Marie Baran wrote:
>
>
> On 15/01/2016 10:52, Moritz Barsnick wrote:
>> On Fri, Jan 15, 2016 at 10:11:09 +0100, Moritz Barsnick wrote:
>>> Would it be worth an attempt to add an option to ffmpeg to take the
>>> timestamps from "arrival time" (time of day)? I'll have a look at this
>>> - sometime.
>> Oh, sorry, that option does exist: "-use_wallclock_as_timestamps".
>>
>> If I record my incoming MJPEG multipart/alternative HTTP stream with
>> "-re -use_wallclock_as_timestamps 1", the timestamps look okay, though
>> astonishingly quite strictly aligned to full seconds. (My stream can
>> vary between 1 fps and 5 fps.)
>>
>>
> Using "-re -use_wallclock_as_timestamps 1" seems right, but sadly it 
> trigger some «Non-monotonous DTS» warning message, and the resulting 
> video now plays too slowly. But this time the fps recorded is 16.52 
> fps which is better than the 25 of before :
>
> ffmpeg -y -thread_queue_size 1024 -f s16le -ar -i 
> tcp://localhost:5419?listen=1 -re -use_wallclock_as_timestamps 1 -f 
> mjpeg -thread_queue_size 1024 -i -c:v libx264 -preset veryfast -crf 28 
> -vsync 0 -strict -2 -acodec aac -threads 0 -ar 44100 file.mp4
>
>
Well, I somewhat solved the problem by removing the "-re" option which 
was preceding "-use_wallclock_as_timestamps". The fps is now guessed 
correctly, and the DTS/PTS things seem to be right. The video plays at 
correct speed when read by ffplay or VLC or whatever, even if I still 
get some warning messages «Past duration 0.xxx too large». If anyone 
gets an idea about this, I'll gladly hear it.

Here is the trace:

ffmpeg version 2.8.3 Copyright (c) 2000-2015 the FFmpeg developers
   built with gcc 4.8 (GCC)
   configuration: --arch=arm --target-os=android --enable-cross-compile
   libavutil      54. 31.100 / 54. 31.100
   libavcodec     56. 60.100 / 56. 60.100
   libavformat    56. 40.101 / 56. 40.101
   libavfilter     5. 40.101 /  5. 40.101
   libavresample   2.  1.  0 /  2.  1.  0
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  2.101 /  1.  2.101
   libpostproc    53.  3.100 / 53.  3.100
Input #0, s16le, from 'tcp://localhost:44722?listen=1':
   Duration: N/A, bitrate: 705 kb/s
     Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
D/AMA.sr.AbusService( 2082): Calling recording_started()
D/amaCnxMgr.pyc(  367): AMA.amaAbusService - recording_started() return 
code: 0
E/amaCnxMgr.pyc(  367): AMA.amaAbusService - Cannot notify the UI that 
the record started: callback not defined
[mjpeg @ 0xb6427c00] Changeing bps to 8
Input #1, mjpeg, from 'pipe:':
   Duration: N/A, start: 1453192324.981191, bitrate: N/A
     Stream #1:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 
720x480 [SAR 1:1 DAR 3:2], 25 tbr, 1200k tbn, 25 tbc
[swscaler @ 0xb6517000] deprecated pixel format used, make sure you did 
set range correctly
[libx264 @ 0xb6428800] using SAR=1/1
[libx264 @ 0xb6428800] using cpu capabilities: ARMv6 NEON
[libx264 @ 0xb6428800] profile High, level 3.0
[libx264 @ 0xb6428800] 264 - core 148 - H.264/MPEG-4 AVC codec - 
Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: 
cabac=1 ref=1 deblock=1:-1:-1 analyse=0x3:0x113 me=hex subme=2 psy=1 
psy_rd=1.00:0.15 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=6 
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=250 
keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=10 rc=crf 
mbtree=1 crf=28.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 
aq=1:1.00
Output #0, mp4, to '/storage/emulated/0/DCIM/AMA/NP/record/./test.mp4':
   Metadata:
     encoder         : Lavf56.40.101
     Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), 
yuv420p, 720x480 [SAR 1:1 DAR 3:2], q=-1--1, 25 fps, 12800 tbn, 25 tbc
     Metadata:
       encoder         : Lavc56.60.100 libx264
     Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 44100 Hz, mono, 
fltp, 128 kb/s
     Metadata:
       encoder         : Lavc56.60.100 aac
Stream mapping:
   Stream #1:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
   Stream #0:0 -> #0:1 (pcm_s16le (native) -> aac (native))
Past duration 0.974800 too large
Past duration 0.746681 too large
Past duration 0.765221 too large
Past duration 0.888924 too large
Past duration 0.992058 too large
Past duration 0.631645 too large
Past duration 0.957054 too large
Past duration 0.698036 too large

-- 
*Jean-Marie Baran*
AMA developer

Skype: jeanmarie.baran
Email: jean-marie.baran at ama.bzh <mailto:jean-marie.baran at ama.bzh>
www.advancedmedicalapplications.com 
<http://www.advancedmedicalapplications.com>
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