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• ffmpeg blocky chroma decoding

  12 septembre 2017, par noiseshaper

  I’m using ffmpeg-3.2.4-win32, static and dev versions from zeranoe page, to decode some h264 mp4 videos I have created with x264 encoder. The videos have lots of static zones, 2d videogame type.

  When I decode their frames using either ffmpeg.exe or avcodec_decode_video2() API function, I get poor chroma resolution, blocky and quite visible in the static zones of the video (edit : avcodec_decode_video2() returns correct YUV, the problem is the YUV->RGB conversion, see my own answer).

  Strangely, with ffmpeg.exe I get poor chroma only if I output the frames to png, but if I output them to jpg, chroma seems much better.

  The videos are 30 fps full hd videos created from static images or from Lagarith RGB captures, converted to YUV with Rec.709 colormatrix and then input to x264.exe using crf 20 and baseline profile. Using high profile makes no difference in my tests (edit : irrelevant, since the problem is in the YUV->RGB conversion).

  If I play a mp4 video with ffplay.exe or MPC HC + LAV decoder, the chroma is good, nearly equal to the uncompressed YUV 4:2:0 version.

  Here is an example of the same frame obtained from a mp4 video created with a static image, the output frame is zoomed in to clearly see the effect.

  https://drive.google.com/file/d/0B5KI1D-N1kHpV3lGaERJRjNkcms/view

  1 : Original frame before compressing.

  2 : YUV 4:2:0 conversion before compressing

  3 : Video output from MPC HC + LAV decoder. ffplay output looks the same.

  4 : Video frames decoded with ffmpeg.exe to jpeg, some jpeg macroblocking is visible.

  5 : Video frames decoded with ffmpeg.exe to png, very blocky chroma. Using avcodec_decode_video2() function, the YUV output or its conversion to RGB produces the same blocky chroma.

  ---

  The command lines for decoding the frames to jpg and png are these :

  ffmpeg -i testcase.mp4 -vf colormatrix=bt709:bt601 -vframes 5 -qscale:v 2 output%03d.jpg

  ffmpeg -i testcase.mp4 -vf colormatrix=bt709:bt601 -vframes 5 output%03d.png

  You can download mp4 and bat files that showcase the effect here :

  https://drive.google.com/drive/folders/0B5KI1D-N1kHpcUdGd2IyM2pXMTg

  ---

  I have tried with ffmpeg 3.2, but same thing happens.

• FFmpeg conversion to Photo-JPEG is blocky [duplicate]

  26 mai 2017, par Richard210363

  This question already has an answer here :

  • ffmpeg generate higher quality images for MJPEG encoding
    
    1 answer
    

  I am converting .mp4 files to .mov with the Photo-JPEG codec to use in After Effects to reduce render times.

  I have looked up the FFmpeg commands to do this and come up with :

  ffmpeg -i tower-bridge.mp4 -an -pix_fmt yuvj420p -vcodec mjpeg -f mov -y tower-bridge.mov 

  This works but when I look at the output video it is quite blocky ; like a mosaic.

  During the conversion I get this message :

  [swscaler @ 0000000008c97fe0] deprecated pixel format used, make sure you did set range correctly

  Research on-line suggests I can ignore this message.

  What can I do to improve the output quality ?

  MediaInfo report on Input file :

  Complete name : F :\london-tower-bridge.mp4
  Format : MPEG-4
  Format profile : Base Media
  Codec ID : isom (isom/avc1/mp42)
  File size : 18.7 MiB
  Duration : 13 s 625 ms
  Overall bit rate : 11.5 Mb/s
  

  ID : 1
  Format : AVC
  Format/Info : Advanced Video Codec
  Format profile : Baseline@L4
  Format settings, CABAC : No
  Format settings, ReFrames : 3 frames
  Codec ID : avc1
  Codec ID/Info : Advanced Video Coding
  Duration : 13 s 625 ms
  Bit rate : 11.5 Mb/s
  Maximum bit rate : 26.8 Mb/s
  Width : 1 920 pixels
  Height : 1 080 pixels
  Display aspect ratio : 16:9
  Frame rate mode : Constant
  Frame rate : 24.000 FPS
  Color space : YUV
  Chroma subsampling : 4:2:0
  Bit depth : 8 bits
  Scan type : Progressive
  Bits/(Pixel*Frame) : 0.231
  Stream size : 18.7 MiB (100%)
  Writing library : Zencoder Video Encoding System
  

  MediaInfo report on Output file :

  Complete name : F :\london-tower-bridge.mov
  Format : MPEG-4
  Format profile : QuickTime
  Codec ID : qt 0000.02 (qt )
  File size : 16.1 MiB
  Duration : 13 s 625 ms
  Overall bit rate mode : Variable
  Overall bit rate : 9 912 kb/s
  Writing application : Lavf57.72.101
  

  ID : 1
  Format : JPEG
  Codec ID : jpeg
  Duration : 13 s 625 ms
  Bit rate mode : Variable
  Bit rate : 9 910 kb/s
  Width : 1 920 pixels
  Height : 1 080 pixels
  Display aspect ratio : 16:9
  Frame rate mode : Constant
  Frame rate : 24.000 FPS
  Color space : YUV
  Chroma subsampling : 4:2:0
  Bit depth : 8 bits
  Scan type : Progressive
  Compression mode : Lossy
  Bits/(Pixel*Frame) : 0.199
  Stream size : 16.1 MiB (100%)
  Language : English
  

• Powerful Video Analytics and Audio Analytics for Piwik

  10 novembre 2016, par InnoCraft — Plugins, Press Releases

  Over the years, one of the most frequently requested feature by users was to be able to measure how videos and audios are watched and engaged with on your website. We are finally able to announce that it is here ! We are very excited to launch Media Analytics, which will help you understand and grow your audience.

  This article is a showcase of the new powerful video and audio analytics product built for Piwik.

  Why media analytics ?

  We all love media content such as videos as they can make our experiences on websites and apps so much more interesting. A growing number of websites now utilize media files in one form or another : a video presentation of a product or service, a video tutorial teaching you how to do something or interviews with key speakers. Also many creators and distributors are publishing audio files such as podcasts or music songs, and even broadcasting live video events such as music concerts or an entire conference online.

  Whenever you publish videos or audio media on your websites or applications, Media Analytics provides you with clear insights on how your audience interacts with your content. It helps you see what content works and why – so you can better understand and further grow your business !

  

  Valuable insights in Real time

  

  See where your audience comes from.

  How will Media Analytics help me grow ?

  • Better understand your audience : who are the users playing videos and for how long, how often, and where have they dropped off.
  • Gain quick insights into how interaction with your media changes over time with easy to use graphs and report overviews.
  • Get closer to your users by seeing every action of your visitors before and after they utilized your media.
  • View valuable insights in Real time : ‘most popular content right now’, your real time audience map, and more.
  • See where your audience comes from. Drill down right from continents to specifics such as cities.
  • Share and export media analytics reports with your colleagues by creating custom email reports.
  • Video and audio players are supported either automatically (for Youtube, Vimeo, HTML5…) or via a simple custom player integration.
  • No data limit and 100% privacy and data ownership.

  Best of all, it is easy to use and understand, and integrates perfectly with Piwik. Media Analytics complements other reports to give you a 360 degree view of how your users engage with your content.

  Learn more on the official website : www.media-analytics.net

  How do I get Media Analytics ?

  All premium plugins come with our 14 day money back guarantee and 1-click installation & updates. Customers get all product updates for free.

  Learn more about Media Analytics Get it now on the Marketplace

  Media Analytics is available for purchase and download on the Marketplace.

  If you are not using Piwik yet, you can also signup for a free trial of Piwik Cloud (including Media Analytics !).

  Have a question about this product ? Get in touch.