Newest 'libx264' Questions - Stack Overflow

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• How to use x264 source code after compiling it

  8 mai 2016, par Zia Khattak

  I need to use the x264 code to compress and stream video from a camera in real time as part of my university project (first using computer and then dsp kit) (and vary quantization value when required). I am totally new to this domain and have absolutely no background.

  So far I have compiled the code using the given method in http://www.ayobamiadewole.com/Blog/How-to-build-x264-or-libx264.dll-in-Windows and created the x264.exe and libx264.dll

  I need help with what to do next in order to use the code for my purpose.

  All help is appreciated.

• CPU spike when transitioning from a still image

  21 avril 2016, par lagnat

  After streaming a still image (with x264) for a long period of time, the transition to live video makes the CPU spike to 100% for a period of time proportionally equal to how long the still image was streaming. More specifically, transitioning after a minute will result in a CPU spike lasting about 15 seconds. Transitioning after 30 minutes will result in that spike lasting closer to 3 minutes.

  Does this symptom make any sense and is there anything I can do about it?

• Why sliced thread affect so much on realtime encoding using ffmpeg x264 ?

  13 avril 2016, par CurtisGuo

  I'm using ffmpeg libx264 to encode a 720p screen captured from x11 in realtime with a fps of 30. when I use -tune zerolatency paramenter, the average encode time per-frame can be as large as 12ms with profile baseline.

  After a study of the ffmpeg x264 source code, I found that the key parameter leading to such long encode time is sliced-threads which enabled by -tune zerolatency. After disabled using -x264-params sliced-threads=0 the encode time can be as low as 2ms

  And with sliced-threads disabled, the CPU usage will be 40%, while only 20% when enabled.

  Can someone explain the details about this sliced-thread? Especially in realtime encoding(assume no frame is buffered to be encoded. only encode when a frame is captured).

• How to encode H.264 video using FFmpeg C API and then open the output with a media player ?

  4 avril 2016, par GummiB

  I'm trying to encode a H.264 video with the FFMPEG C API. I have successfully compiled and executed the decoding/encoding example provided by FFMPEG.

  The problem I'm facing is that the .mpg file (encoded with AV_CODEC_ID_MPEG1VIDEO) the example creates works. Windows creates a thumbnail and everything. On the other hand the .h264 (encoded with AV_CODEC_ID_H264) file does not. When I try to play the file in VLC the play/pause button just flickers, no thumbnail in windows, no nothing.

  During encoding libx264 reports the following:

  [libx264 @ 004b81a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  [libx264 @ 004b81a0] profile High, level 1.3
  [libx264 @ 004b81a0] frame I:3     Avg QP:26.79  size:  2116
  [libx264 @ 004b81a0] frame P:12    Avg QP:26.60  size:   789
  [libx264 @ 004b81a0] frame B:10    Avg QP:31.39  size:   499
  [libx264 @ 004b81a0] consecutive B-frames: 20.0% 80.0%
  [libx264 @ 004b81a0] mb I  I16..4: 78.3% 11.6% 10.1%
  [libx264 @ 004b81a0] mb P  I16..4: 77.4%  0.6%  0.1%  P16..4: 20.3%  0.7%  0.9%  0.0%  0.0%    skip: 0.0%
  [libx264 @ 004b81a0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  9.4%  0.2%  0.0%  direct:11.0%  skip:79.4%  L0:25.4% L1:35.4% BI:39.2%
  [libx264 @ 004b81a0] final ratefactor: 17.03
  [libx264 @ 004b81a0] 8x8 transform intra:3.4% inter:31.3%
  [libx264 @ 004b81a0] direct mvs  spatial:0.0% temporal:100.0%
  [libx264 @ 004b81a0] coded y,uvDC,uvAC intra: 4.4% 35.8% 1.6% inter: 1.3% 34.5% 9.5%
  [libx264 @ 004b81a0] i16 v,h,dc,p:  0%  0%  0% 100%
  [libx264 @ 004b81a0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  7% 20% 17% 49%  0%  0%  0%  1%  6%
  [libx264 @ 004b81a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 14%  7% 18% 45%  2%  7%  2%  3%  2%
  [libx264 @ 004b81a0] i8c dc,h,v,p:  2%  6%  4% 88%
  [libx264 @ 004b81a0] Weighted P-Frames: Y:0.0% UV:0.0%
  [libx264 @ 004b81a0] ref P L0: 95.6%  1.6%  2.2%  0.5%  0.2%
  [libx264 @ 004b81a0] ref B L0: 67.5% 28.5%  3.2%  0.8%
  [libx264 @ 004b81a0] kb/s:166.45
  

  "ffprobe.exe test.h264 -show_streams" returns

  [STREAM]
  index=0
  codec_name=h264
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  profile=High
  codec_type=video
  codec_time_base=1/50
  codec_tag_string=[0][0][0][0]
  codec_tag=0x0000
  width=352
  height=288
  has_b_frames=1
  sample_aspect_ratio=0:1
  display_aspect_ratio=0:1
  pix_fmt=yuv420p
  level=13
  timecode=N/A
  id=N/A
  r_frame_rate=50/2
  avg_frame_rate=25/1
  time_base=1/1200000
  start_pts=N/A
  start_time=N/A
  duration_ts=N/A
  duration=N/A
  bit_rate=N/A
  nb_frames=N/A
  nb_read_frames=N/A
  nb_read_packets=N/A
  DISPOSITION:default=0
  DISPOSITION:dub=0
  DISPOSITION:original=0
  DISPOSITION:comment=0
  DISPOSITION:lyrics=0
  DISPOSITION:karaoke=0
  DISPOSITION:forced=0
  DISPOSITION:hearing_impaired=0
  DISPOSITION:visual_impaired=0
  DISPOSITION:clean_effects=0
  DISPOSITION:attached_pic=0
  [/STREAM]
  

  There you can see:

  start_time=N/A
  duration_ts=N/A
  duration=N/A
  

  I have tried countless changes to the AVCodecContext and multitude of parameters options to av_opt_set function. Still no luck getting a working H.264 video. I have even tried different builds of FFmpeg. No luck.

  I'm using the "FFmpeg git-0fb64da 32-bit Dev" build from Zeranoe and MinGw 4.7.2

• Q.For encoding error of ffmpeg

  21 mars 2016, par 社畜根性

  I ran the following command.

  ffmpeg -i test.mp4 -threads 2 -codec:v libx264 -s:v 1280x720 -aspect:v 16:9 -b:v 256k -map 0 -f segment -segment_format mpegts -segment_time 10 -segment_list stream.m3u8 streamfiles/stream%03d.ts
  

  Execution result

  ffmpeg version N-75926-gce0834b Copyright (c) 2000-2015 the FFmpeg developers
    built with gcc 4.6 (Debian 4.6.3-14+rpi1)
    configuration: --arch=armel --target-os=linux --enable-shared --enable-gpl --enable-libx264 --enable-nonfree
    libavutil      55.  3.100 / 55.  3.100
    libavcodec     57.  5.100 / 57.  5.100
    libavformat    57.  3.100 / 57.  3.100
    libavdevice    57.  0.100 / 57.  0.100
    libavfilter     6. 11.100 /  6. 11.100
    libswscale      4.  0.100 /  4.  0.100
    libswresample   2.  0.100 /  2.  0.100
    libpostproc    54.  0.100 / 54.  0.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
    Metadata:
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2avc1mp41
      encoder         : Lavf56.40.100
    Duration: 00:00:03.28, start: 0.000000, bitrate: 10159 kb/s
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 10156 kb/s, 25 fps, 25 tbr, 1200k tbn, 2400k tbc (default)
      Metadata:
        handler_name    : VideoHandler
  Illegal instruction
  

  The result is that an error occurred. Someone told me that it's an error if you do not put the option to ./configure of libx264. That option is the --extra-cflags='-march=armv6' --extra-ldflags='-march=armv6'. Otherwise it would use the instruction of unsupported.

  So I ran ./configure with the option, then I ran the make and now I'm getting an error message:

  common/arm/quant-a.S: Assembler messages:
  common/arm/quant-a.S:362: Error: selected processor does not support ARM mode `rbit r1,r1'
  common/arm/quant-a.S:363: Error: selected processor does not support ARM mode `rbit r1,r1'
  Makefile:217: recipe for target 'common/arm/quant-a.o' failed
  make: *** [common/arm/quant-a.o] Error 1
  

  I do not know the meaning of this error. How should you deal me this error?

  I use the machine is Raspberry PI B+ and my OS is Raspbian. I want to use ffmpeg and libx264.

  Any advice and suggestions will be greatly appreciated.