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• Prediction is not allowed in AAC-LC

  25 août 2020, par Summit

  I am trying to decode a audio file and the function exits with this message.

  


  [aac @ 0000000000413a00] Prediction is not allowed in AAC-LC.

  


  This error happens at this line ( avcodec_decode_audio4(codec, frame, &gotFrame, &packet))

  


  Why do i get this error ? , How can i correct this.

  


  This is the code for the function to decode the audio frame and i am reading a mp4 file.

  


  int decode_audio_file(const char* path, const int sample_rate, double** data, int* size) {

    // get format from audio file
    AVFormatContext* format = avformat_alloc_context();
    if (avformat_open_input(&format, path, NULL, NULL) != 0) {
        fprintf(stderr, "Could not open file '%s'\n", path);
        return -1;
    }
    else
        std::cout << "File has been opened\n";

    if (avformat_find_stream_info(format, NULL) < 0) {
        fprintf(stderr, "Could not retrieve stream info from file '%s'\n", path);
        return -1;
    }

    // Find the index of the first audio stream
    int stream_index = -1;
    for (int i = 0; i < format->nb_streams; i++) {
        if (format->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
            stream_index = i;
            break;
        }
    }
    if (stream_index == -1) {
        fprintf(stderr, "Could not retrieve audio stream from file '%s'\n", path);
        return -1;
    }
    AVStream* stream = format->streams[stream_index];
    // find & open codec
    AVCodecContext* codec = stream->codec;
    if (avcodec_open2(codec, avcodec_find_decoder(codec->codec_id), NULL) < 0) {
        fprintf(stderr, "Failed to open decoder for stream #%u in file '%s'\n", stream_index, path);
        return -1;
    }

    // prepare resampler
    struct SwrContext* swr = swr_alloc();
    av_opt_set_int(swr, "in_channel_count", codec->channels, 0);
    av_opt_set_int(swr, "out_channel_count", 1, 0);
    av_opt_set_int(swr, "in_channel_layout", codec->channel_layout, 0);
    av_opt_set_int(swr, "out_channel_layout", AV_CH_LAYOUT_MONO, 0);
    av_opt_set_int(swr, "in_sample_rate", codec->sample_rate, 0);
    av_opt_set_int(swr, "out_sample_rate", sample_rate, 0);
    av_opt_set_sample_fmt(swr, "in_sample_fmt", codec->sample_fmt, 0);
    av_opt_set_sample_fmt(swr, "out_sample_fmt", AV_SAMPLE_FMT_DBL, 0);
    swr_init(swr);
    if (!swr_is_initialized(swr)) {
        fprintf(stderr, "Resampler has not been properly initialized\n");
        return -1;
    }
    // prepare to read data
    AVPacket packet;
    av_init_packet(&packet);
    AVFrame* frame = av_frame_alloc();
    if (!frame) {
        fprintf(stderr, "Error allocating the frame\n");
        return -1;
    }

    // iterate through frames
    *data = NULL;
    *size = 0;
    while (av_read_frame(format, &packet) >= 0) {
        // decode one frame
        int gotFrame = 0;
        if (avcodec_decode_audio4(codec, frame, &gotFrame, &packet) < 0) {
            break;
        }
        if (!gotFrame) {
            continue;
        }
        // resample frames
        double* buffer;
        av_samples_alloc((uint8_t**)&buffer, NULL, 1, frame->nb_samples, AV_SAMPLE_FMT_DBL, 0);
        int frame_count = swr_convert(swr, (uint8_t**)&buffer, frame->nb_samples, (const uint8_t**)frame->data, frame->nb_samples);
        // append resampled frames to data
        *data = (double*)realloc(*data, (*size + frame->nb_samples) * sizeof(double));
        memcpy(*data + *size, buffer, frame_count * sizeof(double));
        *size += frame_count;
    }

    // clean up
    av_frame_free(&frame);
    swr_free(&swr);
    avcodec_close(codec);
    avformat_free_context(format);

    // success
    return 0;

}


  


• H.264 : merge fill_rectangle into P-SKIP MV prediction, to match B-SKIP

  6 juillet 2011, par Jason Garrett-Glaser

  H.264 : merge fill_rectangle into P-SKIP MV prediction, to match B-SKIP

• H.264 : merge fill_rectangle into P-SKIP MV prediction, to match B-SKIP

  6 juillet 2011, par Jason Garrett-Glaser

  H.264 : merge fill_rectangle into P-SKIP MV prediction, to match B-SKIP