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• ffmpeg : Fix segfault when using ffmpeg with ffserver where ffmpeg does not supply...

  21 novembre 2011, par Michael Niedermayer

  ffmpeg : Fix segfault when using ffmpeg with ffserver where ffmpeg does not supply...

• Using FFMPEG library in PPAPI : Naclports with FFmpeg

  30 avril 2017, par rasulzhan

  I have configured Webports, ffmpeg ; and I have created the following Makefile for the current project. However, I have met some problem with ffmpeg library linking.

  $ TOOLCHAIN=pnacl make
  
    LINK pnacl/Release/client_unstripped.bc
  
  pnacl/Release/src/client.o: error: undefined reference to 'av_register_all'
  
  make: *** [pnacl/Release/client_unstripped.bc] Error 1

  Can you tell me what I am doing wrong here, my Makefile is shown below :

  VALID_TOOLCHAINS := pnacl glibc clang-newlib win

  NACL_SDK_ROOT ?= $(abspath $(CURDIR)/../..)

  TARGET = client

  OTHERDIR=src

  INC_DIR = inc

  FFMPEG_INC_DIR = ../../toolchain/mac_pnacl/le32-nacl/usr/include

  INCLUDES = -I$(INC_DIR) -I$(FFMPEG_INC_DIR)

  include $(NACL_SDK_ROOT)/tools/common.mk

  CHROME_ARGS += —allow-nacl-socket-api=localhost

  LIBS = nacl_io ppapi_cpp ppapi

  CFLAGS = -Wall -g -O2 $(INCLUDES)
  -L../../toolchain/mac_pnacl/le32-nacl/usr/lib -lavformat \
  -lvpx -lvorbisenc -lvorbis -logg -ltheoraenc -ltheoradec -logg -lmp3lame -lm -pthread -lavcodec -lvpx -lvorbisenc -lvorbis -logg \
  -ltheoraenc -ltheoradec -logg -lmp3lame -lm -pthread -lswresample -lm -lavutil -lm -lavdevice -lavfilter

  SOURCES = $(OTHERDIR)/tcp_util.cc $(OTHERDIR)/tpool.cc
  $(OTHERDIR)/net.cc $(OTHERDIR)/rtsp_response.cc \ $(OTHERDIR)/rtsp.cc
  $(OTHERDIR)/rtsp_common.cc \ $(OTHERDIR)/rtsp_client.cc
  $(OTHERDIR)/udp_util.cc \ $(OTHERDIR)/client.cc

  # Build rules generated by macros from common.mk :

  $(foreach src,$(SOURCES),$(eval $(call
  COMPILE_RULE,$(src),$(CFLAGS))))

  # The PNaCl workflow uses both an unstripped and finalized/stripped binary.
  # On NaCl, only produce a stripped binary for Release configs (not Debug). ifneq (,$(or $(findstring pnacl,$(TOOLCHAIN)),$(findstring
  Release,$(CONFIG)))) $(eval $(call
  LINK_RULE,$(TARGET)_unstripped,$(SOURCES),$(LIBS),$(DEPS))) $(eval
  $(call STRIP_RULE,$(TARGET),$(TARGET)_unstripped)) else $(eval $(call
  LINK_RULE,$(TARGET),$(SOURCES),$(LIBS),$(DEPS))) endif

  $(eval $(call NMF_RULE,$(TARGET),))

  And here is the way, how the library has been used in the class context.

  class VideoDecodePack {
  
  public:
  
      VideoDecodePack() {
  
          av_register_all();
  
      }
  
  };
  
  
  
  class ClientInstance : public pp::Instance {
  
   public:
  
    explicit ClientInstance(PP_Instance instance) : pp::Instance(instance){
  
      cses = InitRtspClientSession();
  
      _videoDecoder = new VideoDecodePack();
  
    }
  
  ...

• ffmpeg replace central channel with ffmpeg

  24 mai 2020, par Rafal B

  I'm trying to replace central channel in the movie (Movie-A) with another audio stream from another movie (Movie-B).
I was able to extract stereo stream from Movie-B :

  



  ffmpeg.exe" -i "Movie-B.mkv"

Stream #0:1(pol): Audio: ac3, 48000 Hz, stereo, fltp, 320 kb/s (default)


  



  and convert it to mono stream :

  



  ffmpeg.exe" -i "Movie-B.mkv" -vn -ab 320k -ac 1 "Movie-B-Audio.ac3"
Output #0, ac3, to 'Movie-B-Audio.ac3':
Stream #0:0(pol): Audio: ac3, 48000 Hz, mono, fltp, 320 kb/s (default)


  



  For Movie-A :

  



  ffmpeg.exe" -i "Movie-B.mkv"
Stream #0:1(eng): Audio: aac (LC), 48000 Hz, 5.1, fltp (default)


  



  so Layout is 5.1 (FL+FR+FC+LFE+BL+BR), not 5.1(side) (FL+FR+FC+SL+SR)

  



  Media Info shows :

  



  Audio
ID: 2
Format: AAC
Format info: Advanced Audio Codec Low Complexity
Commercial name: AAC
Codec ID: A_AAC-2
Bit rate: 426 kb/s
Channel(s): 6 channels
Channel positions: Front: L C R, Side: L R, LFE
Channel layout: C L R Ls Rs LFE


  



  I have extracted all 6 channels into one stream with containing 6 channels :

  



  ffmpeg.exe" -i "Movie-A.mkv" -vn -ab 320k -ac 6 "Movie-A-Audio.ac3"
Output #0, ac3, to 'Movie-A-Audio.ac3':
Stream #0:0(eng): Audio: ac3, 48000 Hz, 5.1, fltp, 320 kb/s (default)


  



  But at this stage I'm getting different Layout in Movie-A-Audio.ac3 :

  



  Audio
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Commercial name                          : Dolby Digital
Duration                                 : 2 h 16 min
Bit rate mode                            : Constant
Bit rate                                 : 320 kb/s
Channel(s)                               : 6 channels
Channel layout                           : L R C LFE Ls Rs


  



  In source Movie-A.mkv it is : Channel layout : C L R Ls Rs LFE

  



  In output Movie-A-Audio.ac3 it is : Channel layout : L R C LFE Ls Rs

  



  Then I tried to extract those 6 channels into separate mono-stream files :

  



  ffmpeg.exe" -i "Movie-A-Audio.ac3" -filter_complex "channelsplit=channel_layout=5.1[FL][FR][FC][LFE][BL][BR]" -ab 320k -ac 1 -map "[FL]" extr_front_left.ac3 -ab 320k -ac 1 -map "[FR]" extr_front_right.ac3 -ab 320k -ac 1 -map "[FC]" extr_front_center.ac3 -ab 320k -ac 1 -map "[LFE]" extr_subwoofer.ac3 -ab 320k -ac 1 -map "[BL]" extr_back_left.ac3 -ab 320k -ac 1 -map "[BR]" extr_back_right.ac3


  



  With result :

  



  Stream mapping:
  Stream #0:0 (ac3) -> channelsplit
  channelsplit:FL -> Stream #0:0 (ac3)
  channelsplit:FR -> Stream #1:0 (ac3)
  channelsplit:FC -> Stream #2:0 (ac3)
  channelsplit:LFE -> Stream #3:0 (ac3)
  channelsplit:BL -> Stream #4:0 (ac3)
  channelsplit:BR -> Stream #5:0 (ac3)
Press [q] to stop, [?] for help
Output #0, ac3, to 'extr_front_left.ac3':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #0:0: Audio: ac3, 48000 Hz, mono, fltp, 320 kb/s
    Metadata:
      encoder         : Lavc58.54.100 ac3
Output #1, ac3, to 'extr_front_right.ac3':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #1:0: Audio: ac3, 48000 Hz, mono, fltp, 320 kb/s
    Metadata:
      encoder         : Lavc58.54.100 ac3
Output #2, ac3, to 'extr_front_center.ac3':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #2:0: Audio: ac3, 48000 Hz, mono, fltp, 320 kb/s
    Metadata:
      encoder         : Lavc58.54.100 ac3
Output #3, ac3, to 'extr_subwoofer.ac3':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #3:0: Audio: ac3, 48000 Hz, mono, fltp, 320 kb/s
    Metadata:
      encoder         : Lavc58.54.100 ac3
Output #4, ac3, to 'extr_back_left.ac3':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #4:0: Audio: ac3, 48000 Hz, mono, fltp, 320 kb/s
    Metadata:
      encoder         : Lavc58.54.100 ac3
Output #5, ac3, to 'extr_back_right.ac3':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #5:0: Audio: ac3, 48000 Hz, mono, fltp, 320 kb/s
    Metadata:
      encoder         : Lavc58.54.100 ac3


  



  When I'm checking channels layouts of those files extracted I see each of them is having Channel Layout marked with Central, for instant front_left.ac3 :

  



  Audio
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Commercial name                          : Dolby Digital
Duration                                 : 2 h 16 min
Bit rate mode                            : Constant
Bit rate                                 : 320 kb/s
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 48.0 kHz


  



  Then I try to join needed channels :

  



  ffmpeg.exe" -i extr_front_left.ac3 -i extr_front_right.ac3 -i Movie-B-Audio.ac3 -i extr_back_left.ac3 -i extr_back_right.ac3 -i extr_subwoofer.ac3 -filter_complex "[0:a][1:a][2:a][3:a][4:a][5:a]join=inputs=6:channel_layout=5.1[a]" -map "[a]" "final-output.ac3


  



  But it is completely messed up : central channel (voice) is heard in front right speaker, in back right speaker is silence (or maybe it is subwoofer ?)

  



  Target is easy :

  



  

  1. convert source stereo central audio channel in Movie-B.mkv to mono channel
and

  


  2. insert it as central channel into Movie-A.mkv that have 5.1 Audio stream with layout C L R Ls Rs LFE

  


  



  So far I was able to complete 1. but I have a problem with mappings.
Can someone try to guide me how to do that ?