Recherche avancée

Sur d’autres sites (4811)

• Anomalie #1876 : Non prise en compte des guillemets dans le surlignage

  14 juin 2011, par cedric -

  voir aussi #2025

• Announcing the first free software Blu-ray encoder

  25 avril 2010, par Dark Shikari — blu-ray, x264

  For many years it has been possible to make your own DVDs with free software tools. Over the course of the past decade, DVD creation evolved from the exclusive domain of the media publishing companies to something basically anyone could do on their home computer.

  But Blu-ray has yet to get that treatment. Despite the “format war” between Blu-ray and HD DVD ending over two years ago, free software has lagged behind. “Professional” tools for Blu-ray video encoding can cost as much as $100,000 and are often utter garbage. Here are two actual screenshots from real Blu-rays : I wish I was making this up.

  But today, things change. Today we take the first step towards a free software Blu-ray creation toolkit.

  Thanks to tireless work by Kieran Kunyha, Alex Giladi, Lamont Alston, and the Doom9 crowd, x264 can now produce Blu-ray-compliant video. Extra special thanks to The Criterion Collection for sponsoring the final compliance test to confirm x264′s Blu-ray compliance.

  With x264′s powerful compression, as demonstrated by the incredibly popular BD-Rebuilder Blu-ray backup software, it’s quite possible to author Blu-ray disks on DVD9s (dual-layer DVDs) or even DVD5s (single-layer DVDs) with a reasonable level of quality. With a free software encoder and less need for an expensive Blu-ray burner, we are one step closer to putting HD optical media creation in the hands of the everyday user.

  To celebrate this achievement, we are making available for download a demo Blu-ray encoded with x264, containing entirely free content !

  On this Blu-ray are the Open Movie Project films Big Buck Bunny and Elephant’s Dream, available under a Creative Commons license. Additionally, Microsoft has graciously provided about 6 minutes of lossless HD video and audio (from part of a documentary project) under a very liberal license. This footage rounds out the Blu-ray by adding some difficult live-action content in addition to the relatively compressible CGI footage from the Open Movie Project. Finally, we used this sound sample, available under a Creative Commons license.

  You may notice that the Blu-ray image is only just over 2GB. This is intentional ; we have encoded all the content on the disk at appropriate bitrates to be playable from an ordinary 4.7GB DVD. This should make it far easier to burn a copy of the Blu-ray, since Blu-ray burners and writable media are still relatively rare. Most Blu-ray players will treat a DVD containing Blu-ray data as a normal Blu-ray disc. A few, such as the Playstation 3, will not, but you can still play it as a data disc.

  Finally, note that (in accordance with the Blu-ray spec) the disc image file uses the UDF 2.5 filesystem, which may be incompatible with some older virtual drive and DVD burning applications. You’ll also need to play it on an actual Blu-ray player if you want to get the menus and such working correctly. If you’re looking to play it on a PC, a free trial of Arcsoft TMT is available here.

  What are you waiting for ? Grab a copy today !

  UPDATE : Here is an AVCHD-compliant version of the above, which should work better when burned on a DVD-5 instead of a BD-R. (mirror)
  

  What’s left before we have a fully free software Blu-ray creation toolkit ? Audio is already dealt with ; AC3 audio (aka Dolby Digital), the format used in DVD, is still supported by Blu-ray, and there are many free software AC3 encoders. The primary missing application is a free software Blu-ray authoring tool, to combine the video and audio streams to create a Blu-ray file structure with the menus, chapters, and so forth that we have all come to expect. But the hardest part is dealt with : we can now create compatible video and audio streams.

  In the meantime, x264 can be used to create streams to be authored using Blu-Print, Scenarist, Encore or other commercial authoring tools.

  More detailed documentation on the new Blu-ray support and how to use it can be found in the official commit message. Do keep in mind that you have to export to raw H.264 (not MKV or MP4) or else the buffering information will be slightly incorrect. Finally, also note that the encoding settings given as an example are not a good choice for general-purpose encoding : they are intentionally crippled by Blu-ray restrictions, which will significantly reduce compression for ordinary non-Blu-ray encoding.

  In addition to Blu-ray support, the aforementioned commit comes with a lot of fun extras :

  x264 now has native variable-framerate ratecontrol, which makes sure your encodes get a correct target bitrate and proper limiting of maximum bitrate even if the duration of every frame is different and the “framerate” is completely unknown. This helps a lot when encoding from variable-framerate container formats such as FLV and WMV, along with variable-framerate content such as anime.

  x264 now supports pulldown (telecine) in much the same fashion as it is handled in MPEG-2. The calling application can pass in flags representing how to display a frame, allowing easy transcoding from MPEG-2 sources with pulldown, such as broadcast television. The x264 commandline app contains some examples of these (such as the common 3:2 pulldown pattern).

  x264 now also exports HRD timing information, which is critical for compliant transport stream muxing. There is currently an active project to write a fully DVB-compatible free software TS muxer that will be able to interface with x264 for a seamless free software broadcast system. It will likely also be possible to repurpose this muxer as part of a free software Blu-ray authoring package.

  All of this is now available in the latest x264.

  http://mirror05.x264.nl/Dark/bluray%20fail.png

• ffmpeg API : handle frame loss in hevc encoding

  8 janvier 2024, par Mario

  Everything works fine until the introduction of frame->pts increment due to frame loss.

  


  Below is the regular progression without frame->pts increments :

  


  


  frame->pts=8 pkt->pts=512 pkt->dts=-512 pkt->flags=1
  
frame->pts=9 pkt->pts=2560 pkt->dts=0 pkt->flags=0
  
frame->pts=10 pkt->pts=1536 pkt->dts=512 pkt->flags=0
  
frame->pts=11 pkt->pts=1024 pkt->dts=1024 pkt->flags=0
  
frame->pts=12 pkt->pts=2048 pkt->dts=1536 pkt->flags=0
  
frame->pts=13 pkt->pts=4608 pkt->dts=2048 pkt->flags=0
  
frame->pts=14 pkt->pts=3584 pkt->dts=2560 pkt->flags=0
  
frame->pts=15 pkt->pts=3072 pkt->dts=3072 pkt->flags=0
  
frame->pts=16 pkt->pts=4096 pkt->dts=3584 pkt->flags=0
  
frame->pts=17 pkt->pts=6656 pkt->dts=4096 pkt->flags=0
  
frame->pts=18 pkt->pts=5632 pkt->dts=4608 pkt->flags=0

  


  


  When I introduce the frame->pts increment it happens :

  


  


  frame->pts=15 pkt->pts=512 pkt->dts=-512 pkt->flags=1
  
frame->pts=17 pkt->pts=4608 pkt->dts=2048 pkt->flags=0
  
frame->pts=19 pkt->pts=2560 pkt->dts=1536 pkt->flags=0
  
[mp4 @ 0x7eff842222c0] Application provided invalid, non monotonically increasing dts to muxer in stream 0 : 2048 >= 1536

  


  


  So I wrote the following code as a "quick" solution (between av_packet_rescale_ts() and av_interleaved_write_frame()) :

  


     av_packet_rescale_ts(pkt, c->time_base, st->time_base);  
   ...
   if (pkt->dts<=previous_dts)  
     {  
      if (pkt->pts<=previous_pts)  
        {  
         pkt->pts=previous_dts+1+pkt->pts-pkt->dts;  
        }  
       pkt->dts=previous_dts+1;  
     }  
   previous_dts=pkt->dts;  
   previous_pts=pkt->pts;  
   ...
   ret = av_interleaved_write_frame(fmt_ctx, pkt);  


  


  Now I no longer have the error, but the values are :

  


  


  frame->pts=15 pkt->pts=512 pkt->dts=-512 pkt->flags=1
  
changed frame->pts=15 pkt->pts=512 pkt->dts=1 pkt->flags=1
  
frame->pts=17 pkt->pts=4608 pkt->dts=2048 pkt->flags=0
  
frame->pts=19 pkt->pts=2560 pkt->dts=1536 pkt->flags=0
  
changed frame->pts=19 pkt->pts=3073 pkt->dts=2049 pkt->flags=0
  
frame->pts=21 pkt->pts=1536 pkt->dts=1536 pkt->flags=0
  
changed frame->pts=21 pkt->pts=2050 pkt->dts=2050 pkt->flags=0
  
frame->pts=23 pkt->pts=4096 pkt->dts=3584 pkt->flags=0
  
frame->pts=25 pkt->pts=8704 pkt->dts=6144 pkt->flags=0
  
frame->pts=27 pkt->pts=6656 pkt->dts=5632 pkt->flags=0
  
changed frame->pts=27 pkt->pts=7169 pkt->dts=6145 pkt->flags=0
  
frame->pts=29 pkt->pts=5632 pkt->dts=5632 pkt->flags=0
  
changed frame->pts=29 pkt->pts=6146 pkt->dts=6146 pkt->flags=0
  
frame->pts=31 pkt->pts=7680 pkt->dts=7168 pkt->flags=0
  
frame->pts=33 pkt->pts=12800 pkt->dts=10240 pkt->flags=0
  
frame->pts=35 pkt->pts=10752 pkt->dts=9728 pkt->flags=0
  
changed frame->pts=35 pkt->pts=11265 pkt->dts=10241 pkt->flags=0
  
frame->pts=37 pkt->pts=9728 pkt->dts=9728 pkt->flags=0
  
changed frame->pts=37 pkt->pts=10242 pkt->dts=10242 pkt->flags=0

  


  


  What is the correct way to handle frame loss scenario ?
Is there a way to inform the encoder about frame loss ?

  


  The encoder is "hevc_qsv" and the output format is mov (.mp4).