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• speeding up x264 encoding (C++ code with libavcodec)

  20 décembre 2012, par Hrishikesh_Pardeshi

  I am trying to capture windows screen (continuous screen shots) and encode them into x264. For that I am using avcodec_encode_video2 function available with libavcodec. However, it takes a huge amount of time. The time fluctuates between 25 – 1800 milliseconds for encoding individual frames.

  I tried tried both 1080p and 720p with video recording on screen.

  These are the settings I am using. This was tested on Windows 7, win32 release build with 4 GB of RAM.

  bit_rate = 2000, width = 1920, height = 1080
  qmin = 0, qmax = 0, max_b_frames = 0, frame_rate = 25, pixel_format = YUV 4:4:4.
  The remaining settings are default which are fetched using avcodec_get_context_defaults3().

  Sample data(in milliseconds) for 20 frames (consecutive and chosen randomly) in a set of 250 frames.
  121, 106, 289, 126, 211, 30, 181, 58, 213, 34, 245, 50, 56, 364, 247, 171, 254, 83, 82, 229

  For the application it is a must that it captures at least at 15 fps. Can someone help out to tell whether any options can be used to improve the frame rate. I need to encode lossless, but I am open to some file size increase.

  Thanks in advance.

• Converting .mp4 to .webm with FFMPEG

  24 septembre 2012, par DAVYM

  Any chance someone can help me make this a 2 or 3 pass command :

  Using "FFmpeg Win64 Static build by Kyle Schwarz, compiled on : Sep 19 2012 16:31:43" in the Command Prompt of Windows7(x64). I am a newbie to FFMPEG and trying to convert videos for my website from .mp4 to .webm (videos edited and mixed in AdobePremiereProCS6 where then encoded into .mp4 from .mts Canon HXG10 recordings). Original video file is 1080p quality.

  c :\ff/ffmpeg -i c :\ff/xxx.mp4 -codec:v libvpx -quality good -cpu-used
  0 -b:v 7000k -qmin 10 -qmax 42 -maxrate 500k -bufsize 1500k -threads 8
  -vf scale=-1:1080 -codec:a libvorbis -b:a 192k -f webm c :\ff/xxx.webm

• What causes Firefox to refuse playing one specific MP4 that plays well on other browsers, resolution being the only difference ?

  3 décembre 2014, par Faro

  I’m a developer for a PHP powered website that allows the upload of videos which get converted to MP4 using ffmpeg. This setup worked pretty well so far, however today I came across a report of a user that couldn’t play one of the files in Firefox.

  I was unable to replicate the issue on my own machine at first, but using a fresh install of Windows 7 I actually got the same issue : The file will not play in Firefox, but works fine in Chrome. If called up directly, Firefox will say "Video can’t be played because the file is corrupt".
  When downloaded, Windows will also not create a thumbnail of the video for the file and WMP will only play the audio part.

  On my own machine the file works perfectly in WMP which made me wonder if it could be a codec issue (I do have the K-Lite Codec Pack installed), however I’ve compared the file to a working one and the only difference is the resolution, filesize and the format profile which is "High@L3.1" for a working file with a 720p resolution and "High@L4.0" for the non-working one (which is 1600x1200).

  I then read through the Wikipedia article on H.264/MPEG-4 AVC and began to wonder if the level might be the issue, and the tool I used (XMedia Recode) actually did not allow me to set a height bigger than 1080 on Level 4, however when I set the level to 5 and encoded the file again, it still wouldn’t play.

  I did find a note on the MDN page of supported formats which reads :

  Firefox/Firefox for Android/Firefox OS supports the format in some cases, but only when a third-party decoder is available, and the device hardware can handle the profile used to encode the MP4.

  I’m assuming that is why the codec pack would allow Firefox to play even the ’broken’ file on my machine, I still don’t understand though why Firefox does play some files but not this one, especially when Chrome on the same machine plays all of them.

  The line in PHP that starts the conversion is as follows :

  exec("/usr/local/bin/ffmpeg '-i' '" . $file_in . "' '-qscale' '4' '-y' '-threads' '1' '-acodec' 'libvo_aacenc' '-vcodec' 'h264' '" . $file_out . "' 2>&1", $buffer, $success);

  This should produce correct files, and this is indeed the first time a file has issues.

  MediaInfo provides this data for the file stream :

  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L4.0
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 4 frames
  
  Codec ID                                 : avc1
  
  Codec ID/Info                            : Advanced Video Coding
  
  Duration                                 : 12mn 26s
  
  Bit rate                                 : 77.7 Kbps
  
  Width                                    : 1 600 pixels
  
  Height                                   : 1 200 pixels
  
  Display aspect ratio                     : 4:3
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 30.000 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.001
  
  Stream size                              : 6.92 MiB (36%)
  
  Writing library                          : x264 core 142 r14 956c8d8
  
  Encoding settings                        : 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 / lookahead_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=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=crf / mbtree=1 / crf=23.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
  
  Language                                 : English
  
  
  
  Audio
  
  ID                                       : 2
  
  Format                                   : AAC
  
  Format/Info                              : Advanced Audio Codec
  
  Format profile                           : LC
  
  Codec ID                                 : 40
  
  Duration                                 : 12mn 26s
  
  Duration_LastFrame                       : -10ms
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 128 Kbps
  
  Channel(s)                               : 2 channels
  
  Channel positions                        : Front: L R
  
  Sampling rate                            : 44.1 KHz
  
  Compression mode                         : Lossy
  
  Stream size                              : 11.4 MiB (60%)
  
  Language                                 : English

  I’ve uploaded a zip with 3 versions of the file, the untouched one, the converted one with the same settings the website would use, and another converted one with level 5.

  Maybe I’m missing something obvious, but I couldn’t find anything wrong with it, what do I need to change in order to produce a file that will work natively in Firefox ?

  Also, this is my first question on SO, so if you see anything that I can improve, please let me know :-)

  Edit : This is the output of calling ffmpeg (with the faststart option)

  /usr/local/bin/ffmpeg '-i' '49cf594e91d0dac376aa0b2b96972ded.mp4' '-movflags' '+faststart' '-qscale' '4' '-y' '-threads' '1' '-acodec' 'libvo_aacenc' '-vcodec' 'h264' 'test.mp4'
  
  
  
  ffmpeg version 1.2.5-   http://johnvansickle.com/ffmpeg/    Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Jan 22 2014 20:28:02 with gcc 4.8 (Debian 4.8.2-14)
  
    configuration: --enable-gpl --enable-version3 --disable-shared --disable-debug --enable-runtime-cpudetect --enable-libmp3lame --enable-libx264 --enable-libspeex --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-gray --enable-libopenjpeg --disable-ffserver
  
    libavutil      52. 18.100 / 52. 18.100
  
    libavcodec     54. 92.100 / 54. 92.100
  
    libavformat    54. 63.104 / 54. 63.104
  
    libavdevice    54.  3.103 / 54.  3.103
  
    libavfilter     3. 42.103 /  3. 42.103
  
    libswscale      2.  2.100 /  2.  2.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  2.100 / 52.  2.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '49cf594e91d0dac376aa0b2b96972ded.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf54.63.104
  
    Duration: 00:12:26.37, start: 0.036281, bitrate: 214 kb/s
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1600x1200 [SAR 1:1 DAR 4:3], 77 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s
  
      Metadata:
  
        handler_name    : SoundHandler
  
  Please use -q:a or -q:v, -qscale is ambiguous
  
  [libx264 @ 0x2802ac0] using SAR=1/1
  
  [libx264 @ 0x2802ac0] using cpu capabilities: MMX2 SSE2Fast LZCNT
  
  [libx264 @ 0x2802ac0] profile High, level 4.0
  
  [libx264 @ 0x2802ac0] 264 - core 142 r14 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - 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 lookahead_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=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'test.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf54.63.104
  
      Stream #0:0(eng): Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1600x1200 [SAR 1:1 DAR 4:3], q=-1--1, 15360 tbn, 30 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(eng): Audio: aac ([64][0][0][0] / 0x0040), 44100 Hz, stereo, s16, 128 kb/s
  
      Metadata:
  
        handler_name    : SoundHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 -> libx264)
  
    Stream #0:1 -> #0:1 (aac -> libvo_aacenc)
  
  Press [q] to stop, [?] for help
  
  Starting second pass: moving header on top of the file30.77 bitrate= 202.5kbits/s dup=1 drop=0
  
  frame=15331 fps= 13 q=29.0 Lsize=   13201kB time=00:08:31.03 bitrate= 211.6kbits/s dup=1 drop=0
  
  video:4673kB audio:7986kB subtitle:0 global headers:0kB muxing overhead 4.286767%
  
  [libx264 @ 0x2802ac0] frame I:63    Avg QP:12.37  size: 39759
  
  [libx264 @ 0x2802ac0] frame P:3905  Avg QP:20.36  size:   313
  
  [libx264 @ 0x2802ac0] frame B:11363 Avg QP:33.67  size:    93
  
  [libx264 @ 0x2802ac0] consecutive B-frames:  1.1%  0.1%  0.2% 98.6%
  
  [libx264 @ 0x2802ac0] mb I  I16..4: 48.0% 41.5% 10.5%
  
  [libx264 @ 0x2802ac0] mb P  I16..4:  0.1%  0.2%  0.0%  P16..4:  0.5%  0.0%  0.0%  0.0%  0.0%    skip:99.1%
  
  [libx264 @ 0x2802ac0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  0.3%  0.0%  0.0%  direct: 0.0%  skip:99.7%  L0:50.2% L1:48.9% BI: 0.8%
  
  [libx264 @ 0x2802ac0] 8x8 transform intra:42.4% inter:36.9%
  
  [libx264 @ 0x2802ac0] coded y,uvDC,uvAC intra: 6.9% 13.4% 9.4% inter: 0.0% 0.1% 0.0%
  
  [libx264 @ 0x2802ac0] i16 v,h,dc,p: 82% 17%  1%  0%
  
  [libx264 @ 0x2802ac0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 30% 20% 49%  0%  0%  0%  0%  0%  0%
  
  [libx264 @ 0x2802ac0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 41% 20% 18%  3%  4%  4%  4%  4%  3%
  
  [libx264 @ 0x2802ac0] i8c dc,h,v,p: 80% 12%  7%  1%
  
  [libx264 @ 0x2802ac0] Weighted P-Frames: Y:0.3% UV:0.3%
  
  [libx264 @ 0x2802ac0] ref P L0: 74.7%  3.8% 10.6% 10.9%  0.0%
  
  [libx264 @ 0x2802ac0] ref B L0: 70.3% 28.9%  0.8%
  
  [libx264 @ 0x2802ac0] ref B L1: 97.9%  2.1%
  
  [libx264 @ 0x2802ac0] kb/s:74.90