Recherche avancée

Sur d’autres sites (11250)

• change wav, aiff or mov audio sample rate of MOV or WAV WITHOUT changing number of samples

  6 mars 2013, par John Pilgrim

  I need a very precise way to speed up audio.
  I am preparing films for OpenDCP, an open-source tool to make Digital Cinema Packages, for screening in theaters.
  My source files are usually quicktime MOV files at 23.976fps with 48.000kHz audio.
  Sometimes my audio is a separate 48.000kHz WAV.
  (FWIW, the video frame rate of the source is actually 24/100.1 frames per second, which is a repeating decimal.)

  The DCP standard is based around a 24.000fps and 48.000kHz program, so the audio and video of the source need to be sped up.
  The image processing workflow inherently involves converting the MOV to a TIF sequence, frame-per-frame, which is then assumed to be 24.000fps, so I don't have to get involved in the internals of the QT Video Media Handler.

  But speeding up the audio to match is proving to be difficult. Most audio programs cannot get the number of audio samples to line up with the retimed image frames. A 0.1% speed increase in Audacity results in the wrong number of samples. The only pathway that I have found that works is to use Apple Cinema Tools to conform the 23.976fps/48.000kHz MOV to 24.000fps/48.048kHz (which it does by changing the Quicktime headers) and then using Quicktime Player to export the audio from that file at 48.000kHz, resampling it. This is frame accurate.

  So my question is : are there settings in ffmpeg or sox that will precisely speed up the audio in a MOV or in a WAV or AIFF precisely ? I would like a cross platform solution, so I am not dependent on Cinema Tools, which is only MacOS.

  I know this is a LOT of background. Feel free to ask clarifying questions !

• Unable to stream swf file with ffserver

  12 août 2014, par user993766

  I’m trying to stream swf w/ flv video & mp3 audio & have had some issues. I believe my ffmpeg command line is fine, I think the problem is with my ffserver configuration. If I comment out the audio configuration, I get video output fine. If I have both, I only get audio - no video. However, upon stopping my input stream, audio will stop and video will start playing(at a faster speed than normal). Saving my ffmpeg to a file & viewing on mplayer yields both audio & video playing at the correct rate.

  Before posting an entire output dump, can anyone tell me if anything is blatantly wrong with my code ?

  FFMPEG is taking in an MPEG2 TS from a digital video tuner, transcoding to flv & mp3 :

  ffmpeg -i /dev/dvb/adapter0/dvr0 -c:v flv -r 15 -c:a mp3 -b:a 128k -ac 1 -ar 44100 http://localhost:8090/feed1.ffm

  My ffserver conf file is :

  Port 8090
  
  BindAddress 0.0.0.0
  
  MaxHTTPConnections 2000
  
  MaxClients 1000
  
  MaxBandwidth 16000
  
  CustomLog -
  
  
  
  <feed>
  
  File /tmp/feed1.ffm
  
  FileMaxSize 5M 
  
  </feed>
  
  
  
  <stream>
  
  Feed feed1.ffm
  
  Format swf
  
  
  
  AudioCodec libmp3lame
  
  AudioBitRate 128k
  
  AudioChannels 1
  
  AudioSampleRate 44100
  
  #AVOptionAudio flags +global_header
  
  
  
  #AVOptionVideo flags +global_header
  
  VideoCodec flv
  
  VideoFrameRate 15
  
  VideoBufferSize 80000
  
  VideoBitRate 100
  
  VideoQMin 1
  
  VideoQMax 5
  
  VideoSize 720x480
  
  PreRoll 0
  
  
  
  </stream>

  I’ve tried all kinds of permutations, adjusting QMax, video size, framerate & VideoBufferSize. Nothing seems to work. Any & all help appreciated !

• How do I decrypt the HLS stream to a .ts file when I have the key and IV ?

  28 décembre 2017, par A___ea_

  I have access to all the .ts files.
  My .m3u8 starts like this :

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXT-X-ALLOW-CACHE:YES
  
  #EXT-X-TARGETDURATION:13
  
  #EXT-X-KEY:METHOD=AES-128,URI="https://localserver/get_key?title_id=144", IV=0x4d1acfe1962002a4abedb8b68c65fa93
  
  #EXTINF:12.066667,
  
  1500_144_00000.ts
  
  #EXTINF:9.000000,
  
  1500_144_00001.ts
  
  EXTINF:9.000000,
  
  1500_144_00002.ts
  
  ...

  ... and the .m3u8 continues to show all the .ts files. It gives me the IV, and my Access key is f0d3321327cbaa1aa9ddba07801607442bebaad65b17ca75a15affd5

  No I’ve been searching my brain and the web for an answer on how to decrypt the .ts files (or the concatenated file) and I have seen suggestions using both openssl and ffmpeg but I can not seem to reach all the way with either tool.

  From what I’ve figured I can use the IV and Access_key to decrypt the stream using openssl. I have used the IV=4d1acfe1962002a4abedb8b68c65fa93 (removed 0x).

  I have so far tried to with the concatenated file :

  openssl aes-128-cbc -d -in concatenatedfile.ts -out decrypted_concatenatedfile.ts -nosalt -iv 4d1acfe1962002a4abedb8b68c65fa93 -K f0d3321327cbaa1aa9ddba07801607442bebaad65b17ca75a15affd5 

  But this just gives me

  bad decrypt
  
  139793444538016:error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt:evp_enc.c:539:

  I’ve seen suggestions that use a .key file and convert that to a readable format. But since I don’t have a .key file, but a ready string, I figure this is where I fail.

  I’ve tried using ffmpeg in accordance to this beautiful post by @aergistal.

  ffmpeg -i my.m3u8 -c copy output.ts

  But here too I seem to fail with my long string key.

  Any suggestions on how to proceed using openssl or ffmpeg are very welcome.

  Kindly