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• Decoding an MKA audio file into raw data of the pcm_alaw type (MKA Audio to pcm_alaw)

  2 octobre 2020, par bbdd

  My task is to open an existing audio file with the mka extension (Matroska container) and extract the raw audio data. If the audio data is different from pcm_alaw, then convert it to pcm_alaw before saving it to another file ( or buffer). This example shows only an example of extracting raw data from an mp2 file. I do not know how to do this with the mka container. I would like to have something like this :

  


  UPD

  


  I found an option to save audio data in the format in which it was recorded in the audio file. An example is shown below.

  


  PS. This is only a test version and most likely there are memory leaks and other problems.

  


  &#xA;#include <qfile>&#xA;#include <qdebug>&#xA;#include "audiodecoder.h"&#xA;&#xA;int main(int argc, char* argv[])&#xA;{&#xA;    AudioDecoder decoder("/home/test/test.mka");&#xA;    bool started = decoder.start();&#xA;    if (!started) {&#xA;        return EXIT_FAILURE;&#xA;    }&#xA;&#xA;    QFile file("/home/test/rawData.bin");&#xA;    file.open(QIODevice::WriteOnly);&#xA;&#xA;    while (true) {&#xA;        auto data = decoder.getData(255);&#xA;        if (data.isEmpty()) {&#xA;            break;&#xA;        }&#xA;        file.write(data.data(), data.size());&#xA;    }&#xA;    file.close();&#xA;    return EXIT_SUCCESS;&#xA;}&#xA;&#xA;</qdebug></qfile>

  


  audiodecoder.h

  


  class AudioDecoder {
public:
    AudioDecoder(const QString& fileName);
    AudioDecoder& operator=(const AudioDecoder& rhs) = delete;
    AudioDecoder& operator=(AudioDecoder&& rhs) = delete;
    AudioDecoder(const AudioDecoder& rhs) = delete;
    AudioDecoder(AudioDecoder&& rhs) = delete;
    virtual ~AudioDecoder(void);

    virtual bool start(void) noexcept;
    virtual QByteArray getData(const quint16& size) noexcept;
    virtual bool stop(void) noexcept;

protected:
    bool m_initialized;
    QString m_fileName;

    AVFrame* p_frame = nullptr;
    AVPacket* p_packet = nullptr;
    AVCodecContext* p_cdcCtx = nullptr;
    AVFormatContext* p_frmCtx = nullptr;
};


  


  audiodecoder.cpp

  


  
static void logging(const char* message)
{
    qDebug() << message;
}

AudioDecoder::AudioDecoder(const QString& fileName)
    : m_initialized(false)
    , m_fileName(fileName)
    , p_cdcCtx(nullptr)
    , p_frmCtx(nullptr)
{
    av_register_all();
}

QByteArray AudioDecoder::getData(const quint16& dataSize) noexcept
{
    QByteArray data;
    qint32 response = 0;
    if (av_read_frame(p_frmCtx, p_packet) >= 0) {
        //logging(QString("AVPacket->pts %1").arg(p_packet->pts).toStdString().c_str());
        //response = decode_packet(p_packet, p_cdcCtx, p_frame);
        response = avcodec_send_packet(p_cdcCtx, p_packet);
        if (response < 0) {
            logging("Error while sending a packet to the decoder");
            return {};
        }
        while (response >= 0) {
            response = avcodec_receive_frame(p_cdcCtx, p_frame);
            if (response == AVERROR(EAGAIN) || response == AVERROR_EOF) {
                break;
            }
            else if (response < 0) {
                logging("Error while receiving a frame from the decoder");
                return {};
            }
            if (response >= 0) {
                logging(QString("Frame %1 (type=%2, size=%3 bytes) pts %4 key_frame %5 [DTS %6], duration[%7]")
                            .arg(p_cdcCtx->frame_number)
                            .arg(av_get_picture_type_char(p_frame->pict_type))
                            .arg(p_frame->pkt_size)
                            .arg(p_frame->pts)
                            .arg(p_frame->key_frame)
                            .arg(p_frame->coded_picture_number)
                            .arg(p_frame->pkt_duration)
                            .toStdString()
                            .c_str());

                for (int i = 0; i < p_frame->linesize[0]; ++i) {
                    data.push_back(p_frame->data[0][i]);
                }
            }
        }
        av_packet_unref(p_packet);
        return data;
    }
    return {};
}

bool AudioDecoder::start(void) noexcept
{
    if (m_initialized) {
        return true;
    }

    int error;
    // Open the input file to read from it.
    if ((error = avformat_open_input(&p_frmCtx,
             m_fileName.toStdString().c_str(), nullptr, nullptr))
        < 0) {
        qDebug() << "Could not open input file: " << m_fileName;
        p_frmCtx = nullptr;
        return false;
    }
    // Get information on the input file (number of streams etc.).
    if ((error = avformat_find_stream_info(p_frmCtx, nullptr)) < 0) {
        avformat_close_input(&p_frmCtx);
        qDebug() << __LINE__;
        return false;
    }
    // Make sure that there is only one stream in the input file.
    if ((p_frmCtx)->nb_streams != 1) {
        avformat_close_input(&p_frmCtx);
        qDebug() << __LINE__;
        return false;
    }

    if (p_frmCtx->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_AUDIO) {
        avformat_close_input(&p_frmCtx);
        qDebug() << __LINE__;
        return false;
    }

    // Find a decoder for the audio stream.
    AVCodec* input_codec = nullptr;
    if (!(input_codec = avcodec_find_decoder((p_frmCtx)->streams[0]->codecpar->codec_id))) {
        avformat_close_input(&p_frmCtx);
        qDebug() << __LINE__;
        return false;
    }
    // Allocate a new decoding context.
    AVCodecContext* avctx = avcodec_alloc_context3(input_codec);
    if (!avctx) {
        avformat_close_input(&p_frmCtx);
        qDebug() << __LINE__;
        return false;
    }
    // Initialize the stream parameters with demuxer information.
    error = avcodec_parameters_to_context(avctx, (p_frmCtx)->streams[0]->codecpar);
    if (error < 0) {
        avformat_close_input(&p_frmCtx);
        avcodec_free_context(&avctx);
        qDebug() << __LINE__;
        return false;
    }
    /* Open the decoder for the audio stream to use it later. */
    if ((error = avcodec_open2(avctx, input_codec, NULL)) < 0) {
        avcodec_free_context(&avctx);
        avformat_close_input(&p_frmCtx);
        qDebug() << __LINE__;
        return false;
    }
    /* Save the decoder context for easier access later. */
    p_cdcCtx = avctx;
    av_dump_format(p_frmCtx, 0, m_fileName.toStdString().c_str(), 0);

    p_frame = av_frame_alloc();
    if (!p_frame) {
        logging("failed to allocated memory for AVFrame");
        return false;
    }
    p_packet = av_packet_alloc();
    if (!p_packet) {
        logging("failed to allocated memory for AVPacket");
        return false;
    }
    return m_initialized = true;
}

bool AudioDecoder::stop(void) noexcept
{
    if (p_cdcCtx != nullptr) {
        avcodec_free_context(&p_cdcCtx);
    }
    if (p_frmCtx != nullptr) {
        avformat_close_input(&p_frmCtx);
    }
    return true;
}

AudioDecoder::~AudioDecoder(void)
{
    stop();
}


  


  But the problem in this example is that I didn't implement the ability to get exactly the requested size of audio data. In my case, it's just ignored. And also, in this case, I extract and save audio data in the format in which it was originally recorded. How do I convert any audio data format to the one I need. For example, I get PCM_S16LE, but I want to convert it to PCM_ALAW.

  


• Trying to change extension of filename on an ffmpeg script

  22 janvier 2019, par prat67

  (first time posting a question here)

  So I’m looking to write a ffmmpeg script to automate encoding my files to VP9.
  The problem I’m having is when I try to strip the extension and add a new one.

  For example
  Demo.mp4

  Should change to
  Demo.webm

  I’m running this on a Ubuntu-16.04 (Server Non-GI Version)
  I’ve tried a few different ways to accomplish this (using google and other posts on StackOverflow) but I can’t seem to make it work

  This is the error I keep getting..

  line 31 : Demo.mp4+.vp9 : syntax error : invalid arithmetic operator (error token is ".mp4+.vp9")

  I’ve also commented (in the code below) where the syntax error is pointing to..

  #!/bin/bash
  
  
  
  # Welcome Message
  
  
  
  clear
  
  printf "====================================\n"
  
  printf "FFMPEG Encoder\n"
  
  printf "(Using HDR-4k Profile)\n"
  
  printf "====================================\n\n"
  
  printf " Loading Files in Current Directory...\n\n"
  
  sleep 3s
  
  
  
  
  
  # Variables
  
  
  
  i=1
  
  ext=".webm"
  
  vadd=4000000
  
  vsub=2000000
  
  
  
  
  
  # Iterate through files in current directory
  
  
  
  for j in *.{mp4,mkv};
  
  do
  
  echo "$i.$j"
  
  file[i]=$j
  
  i=$(( i + 1 ))
  
  done
  
  
  
  
  
  # Select File & Bitrate
  
  
  
  printf "Enter file number\n"
  
  read fselect
  
  printf "${file[$fselect]}: Selected for encoding\n\n"
  
  
  
  printf "Enter Average Bitrate (Eg: 8000000)\n\n"
  
  read bselect
  
  
  
  
  
  # ***THIS IS WHERE THE PROBLEM IS***
  
  # Prepare output file, strip trailing extension (eg .mkv) and add .webm
  
  
  
  ftemp1="${file[$fselect]}"
  
  ftemp2="${ftemp1::-4}"
  
  fout="$(($ftemp2+$ext))"
  
  printf "Output file will be: $fout"
  
  printf "Preparing to encode..."
  
  sleep 5s
  
  
  
  
  
  # Encode with User-Defined Parameters
  
  
  
  ffmpeg -y -report -i ${file[$fselect]} -b:v $bselect -speed 4 -pass 1 \
  
    -pix_fmt yuv420p10le \
  
    -color_primaries 9 -color_trc 16 -colorspace 9 -color_range 1 \
  
    -maxrate "$(($bselect+$vadd))" -minrate "$(($bselect-$vsub))" \
  
    -profile:v 2 -vcodec libvpx-vp9 -f webm /dev/null && \
  
  ffmpeg -y -report -i ${file[$fselect]} -b:v $bselect -pass 2 \
  
    -pix_fmt yuv420p10le \
  
    -color_primaries 9 -color_trc 16 -colorspace 9 -color_range 1 \
  
    -maxrate "$(($bselect+$vadd))" -minrate "$(($bselect-$vsub))" \
  
    -profile:v 2 -vcodec libvpx-vp9 \
  
  $fout

  I’m certain there is a much cleaner way to do this - but I’m not expecting help with that :P

  My suspicion is that I’m trying to add two different types of variables ? But I thought I defined them as strings..I could be wrong

  Please Help... lol

• ffmpeg build from source fails in docker container ?

  24 mars 2016, par John Allard

  I’m trying to make some changes to the ffmpeg source code (yes, I’m a masochist), and to start I booted an Arch Linux docker container, installed the requirements, downloaded ffmpeg source code, and tried to compile, but I’m getting some extremely odd errors.

  compile command :

  ./configure --bindidr=~/ffmpeg_build --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libx264 --enable-nonfree

  Output :

  ./configure:unset:3338: no such has table element: mktemp
  
  pr: /tmp/ffconf.uQI7CeV.c: No such file or directory.
  
  pr: /tmp/ffconf.uQI7CeV.c: No such file or directory.
  
  pr: /tmp/ffconf.uQI7CeV.c: No such file or directory.
  
  pr: /tmp/ffconf.uQI7CeV.c: No such file or directory.
  
  ... (24 times)
  
  pr: /tmp/ffconf.uQI7CeV.c: No such file or directory.
  
  pr: /tmp/ffconf.r547UgWy.m: No such file or directory.
  
  ./configure:53378: parse error near '}'
  
  ==> ERROR" A failure occured in build()
  
      Aborting...
  
  The build failed.

  This doesn’t seem to be a problem with ffmpeg, more a problem with the container. If I check find /tmp -name ffconf\* I see that the files do exist and they contain

  extern int getrusage();
  
  int main(void){ getrusage(); }

  what in the hell is going on ? hash tabled ? mktemp not working ? files not being found ?

  edit-

  here is what is on the line numbers in the files that give the errors

  3338:configure - unset -f mktemp
  
  5338:configure - check_builtin gmtime_r time.g "time_t * time; strict tm*; gmtime_r(time, tm)"

  edit2 - Here’s the dockerfile (cloned from here https://hub.docker.com/r/greyltc/archlinux/ /dockerfile/)

  # Arch Linux baseline docker container
  
  # Generated on Sat Mar 19 14:26:28 GMT 2016 using code in this GitHub repo:
  
  # https://github.com/greyltc/docker-archlinux
  
  FROM scratch
  
  MAINTAINER Grey Christoforo <grey@christoforo.net>
  
  
  
  # copy in super minimal root filesystem archive
  
  ADD archlinux.tar.xz /
  
  
  
  # perform initial container setup tasks
  
  RUN setup-arch-docker-container
  
  
  
  # this allows the system profile to be sourced at every shell
  
  ENV ENV /etc/profile