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• How to extract specific audio track (track 2) from mp4 file using ffmpeg ?

  3 mai 2019, par flash

  I am working on a mp4 file (36017P.mp4) in which I want to extract Track 2 -[English] using ffmpeg.

  

  I tried with the following command on terminal but it seems to extract Track 1 - [English] :

  ffmpeg -i 36017P.mp4 filename.mp3

  Problem Statement :

  I am wondering what changes I need to make in the ffmpeg command above so that it extract Track 2 -[English] from mp4 file.

• Evolution #4487 : Une option sur image_recadre_mini pour vraiment recadrer au mini (et sans garder...

  15 février 2021, par cedric -

  bon j’ai relu tout le code à tête reposé et donc il y a pas de bug, ou plutot la doc est pas claire : la fonction recadre uniquement de manière symétrique haut vs bas et gauche vs droite, pour garder le centre de l’image au centre.
  Donc si tu as un pixel non transparent en 1ère ligne de l’image, le bas ne sera pas recadré non plus.

  Il faudrait donc ajouter une option pour recadrer effectivement au plus juste, indépendamment du centre, mais du coup c’est une évolution et c’est pour plus tard
  (sauf si tu veux proposer une PR prête à l’intégration)

• RAW audio capture from HDMI using DeckLink Mini Recorder 4K

  12 mars 2020, par Amir Raza

  I need to capture audio from TI DSP hardware/Laptop. So I opted "DeckLink Mini Recorder 4K Audio" and it connected to desktop.
  By using Decklink API’s I am able to capture audio (PCM) with 32-bit depth. But when I used media express to capture, and extracted audio
  using FFmpeg and I am getting audio (PCM) with 24-bit depth.

  Question
  1) Does this device "DeckLink Mini Recorder 4K Audio" converts audio from 32-bit to 24-bit ?
  2) Is this device "DeckLink Mini Recorder 4K Audio" bit-exact/loss-less ?

  consider the below test scenario.

  I am playing audio(PCM) by MPC-HC/VLC/Groove player in laptop and capture audio(PCM) using "DeckLink Mini Recorder 4K Audio"
  connected to desktop, The capture audio is bit-exact with the streamed input.?

  i.e ffmpeg.exe -i HDMI_Output1.av1 -vn -c:a copy out.wav

  Note :
  i am using Blackmagic_Desktop_Video_Windows_11.5 & Blackmagic_DeckLink_SDK_11.5 softwares.

  I have added the Decklink API code snippet.

  void main()
  
  {
  
    IDeckLinkIterator* deckLinkIterator = NULL;
  
    IDeckLinkAttributes* deckLinkAttributes = NULL;
  
    IDeckLink* deckLink = NULL;
  
    IDeckLinkInput* deckLinkInput = NULL;
  
    NotificationCallback* notificationCallback = NULL;
  
    HRESULT result;
  
    BOOL supported;
  
    int returnCode = 1;
  
  #ifdef WRITE_WAV_FILE
  
    wave_header wh;
  
    unsigned octet_depth;
  
  #endif
  
    Initialize();
  
  #ifdef _WIN32
  
    MutexHandle = CreateMutex(NULL, /* security attributes */
  
                              FALSE, /* initially not owned */
  
                              NULL); /* Name */
  
  #endif
  
    /* Create an IDeckLinkIterator object to enumerate all DeckLink cards in the system */
  
    if (GetDeckLinkIterator(&deckLinkIterator) != S_OK)
  
    {
  
      fprintf(stderr, "A DeckLink iterator could not be created.  The DeckLink drivers may not be installed.\n");
  
      goto bail;
  
    }
  
    /* Obtain the first DeckLink device */
  
    result = deckLinkIterator->Next(&deckLink);
  
    if (result != S_OK)
  
    {
  
      fprintf(stderr, "Could not find DeckLink device - result = %08x\n", result);
  
      goto bail;
  
    }
  
  
  
    /* Obtain the Attributes interface for the DeckLink device */
  
    result = deckLink->QueryInterface(IID_IDeckLinkAttributes, (void**)&deckLinkAttributes);
  
    if (result != S_OK)
  
    {
  
      fprintf(stderr, "Could not obtain the IDeckLinkAttributes interface - result = %08x\n", result);
  
      goto bail;
  
    }
  
  
  
    /* Determine whether the DeckLink device supports input format detection */
  
    result = deckLinkAttributes->GetFlag(BMDDeckLinkSupportsInputFormatDetection, &supported);
  
    if ((result != S_OK) || (supported == false))
  
    {
  
      fprintf(stderr, "Device does not support automatic mode detection\n");
  
      goto bail;
  
    }
  
  
  
    /* Obtain the input interface for the DeckLink device */
  
    result = deckLink->QueryInterface(IID_IDeckLinkInput, (void**)&deckLinkInput);
  
    if (result != S_OK)
  
    {
  
      fprintf(stderr, "Could not obtain the IDeckLinkInput interface - result = %08x\n", result);
  
      goto bail;
  
    }
  
  
  
    /* Create an instance of notification callback */
  
    notificationCallback = new NotificationCallback(deckLinkInput);
  
    if (notificationCallback == NULL)
  
    {
  
      fprintf(stderr, "Could not create notification callback object\n");
  
      goto bail;
  
    }
  
  
  
    /* Set the callback object to the DeckLink device's input interface */
  
    result = deckLinkInput->SetCallback(notificationCallback);
  
    if (result != S_OK)
  
    {
  
      fprintf(stderr, "Could not set callback - result = %08x\n", result);
  
      goto bail;
  
    }
  
  
  
    /*  Enable video input with a default video mode and the automatic format detection feature enabled */
  
    result = deckLinkInput->EnableVideoInput(bmdModeHD1080p5994, bmdFormat8BitYUV, bmdVideoInputFlagDefault);
  
    if (result != S_OK)
  
    {
  
      fprintf(stderr, "Could not enable video input - result = %08x\n", result);
  
      goto bail;
  
    }
  
    nBytesPerSample = (bmdAudioSampleType32bitInteger >> 3);
  
    nChannels = 2;
  
    /*  Enable audio input with a default audio mode and the automatic format detection feature enabled */
  
    result = deckLinkInput->EnableAudioInput(bmdAudioSampleRate48kHz, bmdAudioSampleType32bitInteger, nChannels);
  
    if (result != S_OK)
  
    {
  
      fprintf(stderr, "Could not enable audio input - result = %08x\n", result);
  
      goto bail;
  
    }
  
  
  
  #ifdef WRITE_WAV_FILE
  
    /* Populate the wave headers */
  
    /* RIFF */
  
    sprintf(&wh.riff.name1[0], "RIFF");
  
    sprintf(&wh.riff.name2[0], "WAVE");
  
    /* format */
  
    octet_depth = (bmdAudioSampleType32bitInteger + 7) / 8;
  
    sprintf(&wh.fmt.name[0], "fmt ");
  
    wh.fmt.size = FMT_SIZE;
  
    wh.fmt.format_type = FMT_TAG_PCM;
  
    wh.fmt.channel_count = (unsigned short)nChannels;
  
    wh.fmt.sample_rate = bmdAudioSampleRate48kHz;
  
    wh.fmt.bits_per_sample = (unsigned short)octet_depth * 8;
  
    wh.fmt.block_alignment = (unsigned short)(octet_depth*nChannels);
  
    wh.fmt.bytes_per_second = (unsigned long)wh.fmt.block_alignment*bmdAudioSampleRate48kHz;
  
    wh.fmt.extra_bytes = (unsigned short)0;
  
    /* data */
  
    sprintf(&wh.data.name[0], "data");
  
  #endif 
  
  
  
    printf("Starting streams\n");
  
  
  
    /* Start capture */
  
    result = deckLinkInput->StartStreams();
  
    if (result != S_OK)
  
    {
  
      fprintf(stderr, "Could not start capture - result = %08x\n", result);
  
      goto bail;
  
    }
  
  #ifdef WRITE_WAV_FILE
  
    FILE *fp = fopen("HDMI_Output.wav", "wb");
  
  #else
  
    FILE *fp = fopen("HDMI_Output.bin","wb");
  
  #endif
  
    char *ptrCopy;
  
    float *fPtr;
  
    unsigned int zeroCntr, trailingZerosCnt;
  
    do
  
    {
  
        zeroCntr = 0;
  
        trailingZerosCnt = 0;
  
  #ifdef _WIN32
  
        WaitForSingleObject(MutexHandle, /* handle */
  
                            INFINITE); /* time-out interval */
  
  #endif
  
        int bytesInQueue = (int)((long long)aBufPtr - (long long)aBufWritePtr);
  
        ptrCopy = (char *)aBufPtr;
  
  #ifdef _WIN32
  
        ReleaseMutex(MutexHandle);
  
  #endif
  
        if (bytesInQueue > 0)
  
        {
  
  #ifdef STRIP_ZEROS
  
            /* Parse data for zeros */
  
            fPtr = (float *)aBufWritePtr;
  
            for (int i = 0; i < (bytesInQueue >> 2); i++)
  
            {
  
                if (*(fPtr + i) == 0.0)
  
                    zeroCntr++;
  
                else
  
                    break;
  
            }
  
            aBufWritePtr += (zeroCntr << 2);
  
            bytesInQueue -= (zeroCntr << 2);
  
  #endif
  
            if (bytesInQueue > 0)
  
            {
  
                fPtr = (float *)aBufWritePtr;
  
                for (int i = 0; i < (bytesInQueue >> 2); i++)
  
                {
  
                    fwrite(fPtr, 4, 1, fp);
  
                    fflush(fp);
  
  
  
                    if (*fPtr == 0.0)
  
                        trailingZerosCnt++;
  
                    else
  
                        trailingZerosCnt = 0;
  
  
  
                    if (trailingZerosCnt >= NUM_TRAIL_ZEROS_TRESHOLD)
  
                        break;
  
  
  
                    fPtr++;
  
                }
  
            }
  
        }
  
        aBufWritePtr = ptrCopy;
  
        Sleep(100);
  
    } while (trailingZerosCnt < NUM_TRAIL_ZEROS_TRESHOLD);
  
  
  
    fclose (fp);
  
  #ifdef STRIP_ZEROS
  
    /* Remove trailing zeros, write wave header */
  
  #ifdef WRITE_WAV_FILE
  
    fp = fopen("HDMI_Output.wav", "rb");
  
  #else
  
    fp = fopen("HDMI_Output.bin", "rb");
  
  #endif
  
    fseek(fp, 0, SEEK_END);
  
    int size = ftell(fp);
  
    size = size - (NUM_TRAIL_ZEROS_TRESHOLD << 2);
  
    printf(" \n size of hearder = %d", size);
  
  #ifdef WRITE_WAV_FILE
  
    wh.data.size = size;
  
    wh.riff.size = wh.data.size + sizeof(wave_format) + sizeof(wave_RIFF);
  
    printf(" \n size of hearderwh.riff.size = %d", wh.riff.size);
  
  #endif
  
    char * tmpBuf = (char *)malloc(size);
  
    fseek(fp, 0, SEEK_SET);
  
    fread(tmpBuf, 1, size, fp);
  
    fclose(fp);
  
  #endif
  
  #ifdef WRITE_WAV_FILE
  
    fp = fopen("HDMI_Output.wav", "wb");
  
    /* write the wave header */
  
    fwrite(&wh, 1, sizeof(wave_header), fp);
  
    /* Write the zero stripped PCM data */
  
    fwrite(tmpBuf, 1, size, fp);
  
    free(tmpBuf);
  
    fflush(fp);
  
    fclose(fp);
  
  #endif
  
  bail:
  
    /* Stop capture */
  
    result = deckLinkInput->StopStreams();
  
  
  
    /* Disable the video input interface */
  
    result = deckLinkInput->DisableVideoInput();
  
  
  
    /* return success */
  
    returnCode = 0;
  
  
  
    /* Release resources */
  
  
  
    /* Release the attributes interface */
  
    if (deckLinkAttributes != NULL)
  
      deckLinkAttributes->Release();
  
  
  
    /* Release the video input interface */
  
    if (deckLinkInput != NULL)
  
      deckLinkInput->Release();
  
  
  
    /* Release the Decklink object */
  
    if (deckLink != NULL)
  
      deckLink->Release();
  
  
  
    /* Release the DeckLink iterator */
  
    if (deckLinkIterator != NULL)
  
      deckLinkIterator->Release();
  
  
  
    /* Release the notification callback object */
  
    if (notificationCallback)
  
      delete notificationCallback;
  
  }