Recherche avancée

Sur d’autres sites (5448)

• How to increase the compression ratio of a JPEG2000 file with "avenc_jpeg2000" GStreamer encoder ?

  10 juillet 2023, par qfr.bertin.group

  I'm using the plugin avenc_jpeg2000, from gst-libav module, combined with videotestsrc and filesink plugins for encoding a raw picture to a JPEG2000 picture :

  


  gst-launch-1.0 videotestsrc num-buffers=1 ! avenc_jpeg2000 ! filesink location=/tmp/picture-ref.jp2


  


  This pipeline works and produce a 31.85 KiB (32,616) file.

  


  Pipeline graph

  


  Now, I want to divide the size of my output file by two by increasing the compression ratio of the encoder avenc_jpeg2000. To achieve this, I want to minimize the number of bits required to represent the image with an allowable level of distortion. I know JPEG2000 standard support lossless and lossy compression mode. For my use case, the lossy compression mode is acceptable.

  


  How should I proceed to increase the compression of my output file ? What encoder's properties should I play with for doing that ?

  


  My test configuration :

  


  


  • i.MX 8M Plus

    


  


  • GStreamer 1.18.0

    


  


  • libav 1.18.0 (Release date : 2020-09-08)

    


  


  


  I tried to play with "bitrate" and "bitrate-tolerance" properties, but it seems to have no effect on the size of the output file :

  


  gst-launch-1.0 videotestsrc num-buffers=1 ! avenc_jpeg2000 bitrate=100000 bitrate-tolerance=10000 ! filesink location=/tmp/picture-test-01.jp2


  


  I compare files by doing a checksum with sha224sum command :

  


  d0da9118a9c93a0420d6d62f104e0d99fe6e50cda5e87a46cef126f9  /tmp/picture-ref.jp2

d0da9118a9c93a0420d6d62f104e0d99fe6e50cda5e87a46cef126f9  /tmp/picture-test-01.jp2


  


• How to determine the proper HTML5 video codec attribute for an AV1 file based on the FFMpeg encoding command or output ?

  20 décembre 2020, par Slbox

  We have some files encoded in AV1, but we recently noticed that Chrome mobile fails to play the files - but it doesn't fall back to an encoding it can use - it just puts the unplayable AV1 file in there. I'm hoping that if we add a codec attribute we can remedy this - but I'm not sure how to determine the codec for these AV1 files.

  


  I've come across this documentation on MDN, but I'm not sure how I would determine the proper codec from that. It starts off simple enough, but some of the values further down, I have no idea what the right value would be.

  


  Opening the file in VLC player only shows this very limited information about the codec :

  


  

  


  The output of MediaInfo is :

  


  General
Complete name                            : demo-av1.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/mp41)
File size                                : 291 KiB
Duration                                 : 1 min 40 s
Overall bit rate                         : 23.7 kb/s
Writing application                      : Lavf58.43.100

Video
ID                                       : 1
Format                                   : AV1
Format/Info                              : AOMedia Video 1
Format profile                           : High@L3.0
Codec ID                                 : av01
Duration                                 : 1 min 40 s
Bit rate                                 : 22.9 kb/s
Width                                    : 984 pixels
Height                                   : 670 pixels
Display aspect ratio                     : 3:2
Frame rate mode                          : Constant / Constant
Frame rate                               : 24.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:4:4
Bit depth                                : 8 bits
Scan type                                : Progressive / Progressive
Bits/(Pixel*Frame)                       : 0.001
Stream size                              : 281 KiB (96%)
Color range                              : Limited
Codec configuration box                  : av1C / av1C


  


  The command to create the files and the output of FFMpeg is like so :

  


  
ffmpeg -y -i "D:\RAW VIDEO\Demos\demo.avi" -ss 00:00:00  -c:v libaom-av1 -pix_fmt yuv444p -minrate 500 -b:v 48k -maxrate 1000k -strict experimental -movflags +faststart -f mp4 NUL && ffmpeg -y -i "D:\RAW VIDEO\Demos\demo.avi" -ss 00:00:00  -c:v libaom-av1 -pix_fmt yuv444p -minrate 500 -b:v 48k -maxrate 1000k -strict experimental -movflags +faststart -pass 2 "D:\RAW VIDEO\Demos\converted\demo-av1.mp4"
ffmpeg version git-2020-05-22-38490cb Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200513

  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 46.100 / 56. 46.100
  libavcodec     58. 86.101 / 58. 86.101
  libavformat    58. 43.100 / 58. 43.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 82.100 /  7. 82.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100

Input #0, avi, from 'D:\RAW VIDEO\Demos\demo.avi':
  Metadata:
    encoder         : Lavf58.29.100
  Duration:
00:00:23.43, start: 0.000000, bitrate: 19719 kb/s
    Stream #0:0: Video: huffyuv (HFYU / 0x55594648), bgr0, 420x240, 19739 kb/s, 30 fps, 30 tbr, 30 tbn, 30 tbc

Stream mapping:
  Stream #0:0 -> #0:0 (huffyuv (native) -> av1 (libaom-av1))

Press [q] to stop, [?] for help

[libaom-av1 @ 00000000003fb3c0] v1.0.0

Output #0, mp4, to 'NUL':
  Metadata:
    encoder         : Lavf58.43.100

    Stream #0:0: Video: av1 (libaom-av1) (av01 / 0x31307661), yuv444p, 420x240, q=-1--1, 48 kb/s, 30 fps, 15360 tbn, 30 tbc
    Metadata:
      encoder         : Lavc58.86.101 libaom-av1
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A




  


• Use FFMPEG without downloading full file

  19 août 2020, par servalex

  I'm generating thumbnails for a videos that are available from s3 and need to minimize traffic.
Frame is going to be from the first couple seconds of the video so the question : is there a way to get frame without passing the full file through network ?

  


  At the moment I'm passing video url to ffmpeg but seems like it downloads the whole file, not only first couple seconds.

  


  ffmpeg -ss 0 -noaccurate_seek -i {srcPresignedUrl} -vframes 1 -q:v 2 {outputFileName}

  


  I tried downloading first 10mb of the file and passing it, this works for some mp4 files, but fails on mov :

  


  ffmpeg.exe -ss 0 -i source.mov -vframes 1 -q:v 2 thumb.jpg
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.2.1 (GCC) 20200726
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --enable-librav1e --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000017582ffff40] moov atom not found
source.mov: Invalid data found when processing input