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• Live Streaming WebM with Wowza Server

  2 décembre 2010, par noreply@blogger.com (John Luther)

  Guest blogger Charlie Good is CTO and co-founder of Wowza Media Systems

  As a company, we at Wowza move fast and like to tinker. When WebM was announced in May, we saw it as a promising new approach to HTML5 video and decided to do an experiment with live WebM streaming over http.

  Adding WebM VP8 video and Vorbis audio to the other encoding formats that our server supported was easy (we designed the Wowza server to be codec-agnostic). We then created a WebMfile and implemented WebM HTTP streaming.

  We originally created the demo as a proof-of-concept for the IBC show in September, 2010 but have made it available to watch on our web site.

  The file is streamed live (more precisely, "pseudo-live") over http using the Wowza server-side publishing API (PDF). The result is very impressive ; playback starts fast and the VP8 image quality is fantastic.

  You will need a WebM-enabled browser or VLC media player 1.1.5 to view the live stream.

  If you’re interested in keeping up with Wowza’s WebM progress, visit Wowza Labs or drop us a note at info@wowzamedia.com.

  

• avcodec/speexdec : Consider mode in frame size check

  26 décembre 2021, par Michael Niedermayer

  avcodec/speexdec : Consider mode in frame size check
  No speex samples with non default frame sizes are known (to me)
  
  the official speexenc seems to only generate the 3 default ones.
  
  Thus it may be that the fuzzer samples where the first non default
  
  values encountered by the decoder.
  
  Possibly the "<" should be " !="
  Fixes : out of array access
  
  Fixes : 42821/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SPEEX_fuzzer-5640695772217344
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/speexdec.c

• three ways to achieve an H264 file

  18 mars 2016, par Kindermann

  here I have three ways to get an H264 file, like all forensic scientists, I am very curious about the differences between them :

  1.

  ffmpeg -i video.mp4 video.h264

  2.

  ffmpeg -i video.mp4 -vcodec copy -an -f h264 video.h264

  3. Using the example "demuxing_decoding.c" provided on the ffmpeg official website :
  http://ffmpeg.org/doxygen/trunk/demuxing_decoding_8c-example.html

  Obviously, the first one does the transformation, and the second one does the demuxing. They render different H264 files which however have similar file sizes(in my case, it’s about say 24 MB). Suprisingly, the third one, which is also supposed to do the demuxing job, renders an H264 file with 8.4 GB ! Why ?

  What I wondered is really, how the interiors of these three methods work ?(The third one is already in source code, therefore it’s quite easy to have an insight) What about the first two commands ? What APIs are called when executing these two commands and how those APIs are called(namely, in what kind of sequences they are called) and things like that.
  One thing that is also important to me is, i have no idea how I can trace the execution routines of ffmpeg command lines. I want to see what’s going on behind ffmpeg commands in source code version. Is it possible ?

  I appreciate any comment.