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• CoreAudio Output Sample Rate Discrepancy

  1er mai 2018, par blackirishman

  I am using ffmpeg to acquire audio from .mov files. Looking over my settings, I am not sample rate converting the audio buffers I am generating so that is unlikely to account for the issues I am having. Regardless of the sample rate I set on my Built-in Output, my audio files that are at 44.1 kHz playback at the correct rate. If I playback a 48kHz file, the file plays back slower (at 91% of the normal rate) which indicates that the true rate is 44.1kHz. I can change my built-in output to 44.1, 48, or 96 kHz and the same phenomenon exists. I change my default output rate using the Audio Midi Setup app. I then verify my sample rate using AudioUnitGetProperty on my ouputAudioUnit. This matches the sample rate in the Audio Midi Setup.

  Thoughts ? I am including my audio graph code

  CheckError(NewAUGraph(&fp.graph), "Couldn't create a new AUGraph");
  
  
  
  //varispeednode has an input callback
  
  //the vairspeed node feeds an output node which is running 
  
  //at the frequency of the system default output
  
  
  
  AUNode outputNode;
  
  AudioComponentDescription outputcd = [self defaultOutputComponent];
  
  CheckError(AUGraphAddNode(fp.graph, &outputcd, &outputNode),
  
             "AUGraphAddNode[kAudioUnitSubType_DefaultOutput] failed");
  
  
  
  AUNode varispeedNode;
  
  AudioComponentDescription varispeedcd = [self variSpeedComponent];
  
  CheckError(AUGraphAddNode(fp.graph, &varispeedcd, &varispeedNode),
  
             "AUGraphAddNode[kAudioUnitSubType_Varispeed] failed");
  
  
  
  CheckError(AUGraphOpen(fp.graph),
  
             "Couldn't Open AudioGraph");
  
  
  
  CheckError(AUGraphNodeInfo(fp.graph, outputNode, NULL, &fp.outputAudioUnit),
  
             "Couldn't Retrieve output node");
  
  
  
  CheckError(AUGraphNodeInfo(fp.graph, varispeedNode, NULL, &fp.variSpeedAudioUnit),
  
             "Couldn't Retrieve Varispeed Audio Unit");
  
  
  
  AURenderCallbackStruct input;
  
  input.inputProc = CBufferProviderCallback;
  
  input.inputProcRefCon = &playerStruct;
  
  CheckError(AudioUnitSetProperty(fp.variSpeedAudioUnit,
  
                                  kAudioUnitProperty_SetRenderCallback, 
  
                                  kAudioUnitScope_Input,
  
                                  0,
  
                                  &input, 
  
                                  sizeof(input)),
  
             "AudioUnitSetProperty failed");
  
  
  
  
  
  CheckError(AUGraphConnectNodeInput(fp.graph, varispeedNode, 0, outputNode, 0),
  
             "Couldn't Connect varispeed to output");
  
  
  
  CheckError(AUGraphInitialize(fp.graph),
  
             "Couldn't Initialize AUGraph");
  
  
  
  // check output sample rate
  
  
  
  Float64 outputSampleRate = 48000.0;
  
  UInt32 sizeOfFloat64 = sizeof(Float64);
  
  
  
  outputSampleRate = 0.0;
  
  CheckError(AudioUnitGetProperty(fp.outputAudioUnit,
  
                                 kAudioUnitProperty_SampleRate,
  
                                 kAudioUnitScope_Global,
  
                                 0,
  
                                 &outputSampleRate,
  
                                 &sizeOfFloat64), 
  
            "Couldn't get output sampleRate");

• jpeg2000dec ; optimize output sample convert a bit

  1er juin 2013, par Michael Niedermayer

  jpeg2000dec ; optimize output sample convert a bit
  67935 -> 29984 kcycles
  Reviewed-by : Nicolas BERTRAND <nicoinattendu@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/jpeg2000dec.c

• FFmpeg change audio sample rate

  18 juin 2017, par Val Pan

  I need to increase the sample rate by 10%. Sample rates of input files are unknown.

  I found this. Example for 1 file :

  ffmpeg -i xxx.mp3 -filter:a "asetrate=$(ffprobe -v error -show_entries stream=sample_rate -of default=noprint_wrappers=1:nokey=1 xxx.mp3)*1.1" -y xxx1.mp3

  But is is not working and creates 0kb file.

  LOG :

  [asetrate @ 00000000024242e0] [Eval @ 00000000005fde80] Undefined
  constant or missing ’(’ in
  ’ffprobe-verror-show_entriesstream=sample_rate-ofdefault=noprint_wrappers=1’
  [asetrate @ 00000000024242e0] Unable to parse option value "$(ffprobe
  -v error -show_entries stream=sample_rate -of default=noprint_wrappers=1" [Parsed_asetrate_0 @ 0000000000e6cb20]
  Option ’nokey’ not found [AVFilterGraph @ 0000000002419ca0] Error
  initializing filter ’asetrate’ with args ’$(ffprobe -v error
  -show_entries stream=sample_rate -of default=noprint_wrappers=1:nokey=1 xxx.mp3)*1.1’ Error reinitializing
  filters ! Failed to inject frame into filter network : Option not found
  Error while processing the decoded data for stream #0:0 Conversion
  failed !