extract audio from media file

/*
 * Copyright (c) 2010 Nicolas George
 * Copyright (c) 2011 Stefano Sabatini
 * Copyright (c) 2012 Clément Bœsch
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
/**
 * @file
 * API example for audio decoding and filtering
 * @example filtering_audio.c
 */


#include "MediaExtractionTools.h"
#include <iostream>
#include <hlcam-common.h>

#ifdef __cplusplus
extern "C" {
#endif
#include <unistd.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavfilter/avfiltergraph.h>
#include <libavfilter/avcodec.h>
#include <libavfilter/buffersink.h>
#include <libavfilter/buffersrc.h>
#include <libavutil/opt.h>
#include <libavutil/frame.h>


#ifndef M_PI
#define M_PI 3.1415926535897931
#endif

static const char *filter_descr = "aresample=8000,aformat=sample_fmts=s16:channel_layouts=mono";
static const char *player       = "ffplay -f s16le -ar 8000 -ac 1 -";
static AVFormatContext *fmt_ctx;
static AVCodecContext *dec_ctx;

AVFilterContext *buffersink_ctx;
AVFilterContext *buffersrc_ctx;
AVFilterGraph *filter_graph;
static int audio_stream_index = -1;

static int open_input_file(const char *filename)
{
    int ret;
    AVCodec *dec;
    if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
        return ret;
    }
    if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
        return ret;
    }
    /* select the audio stream */
    ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, &dec, 0);
    if (ret < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot find a audio stream in the input file\n");
        return ret;
    }
    audio_stream_index = ret;
    dec_ctx = fmt_ctx->streams[audio_stream_index]->codec;
    av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
    /* init the audio decoder */
    if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot open audio decoder\n");
        return ret;
    }
    return 0;
}


static int init_filters(const char *filters_descr)
{
    char args[512];
    int ret = 0;
    AVFilter *abuffersrc  = avfilter_get_by_name("abuffer");
    AVFilter *abuffersink = avfilter_get_by_name("abuffersink");
    AVFilterInOut *outputs = avfilter_inout_alloc();
    AVFilterInOut *inputs  = avfilter_inout_alloc();
    static const enum AVSampleFormat out_sample_fmts[] = { AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE };

    static const int64_t out_channel_layouts[] = { AV_CH_LAYOUT_MONO, AV_SAMPLE_FMT_NONE };
    static const int out_sample_rates[] = { 8000, -1 };
    const AVFilterLink *outlink;
    AVRational time_base = fmt_ctx->streams[audio_stream_index]->time_base;
    filter_graph = avfilter_graph_alloc();
    if (!outputs || !inputs || !filter_graph) {
        ret = AVERROR(ENOMEM);
        goto end;
    }
    /* buffer audio source: the decoded frames from the decoder will be inserted here. */
    if (!dec_ctx->channel_layout)
        dec_ctx->channel_layout = av_get_default_channel_layout(dec_ctx->channels);
        snprintf(args, sizeof(args),
            "time_base=%d/%d:sample_rate=%d:sample_fmt=%s:channel_layout=0x%llx", // substituted 11x for PRIx64 macro
             time_base.num, time_base.den, dec_ctx->sample_rate,
             av_get_sample_fmt_name(dec_ctx->sample_fmt), dec_ctx->channel_layout);
    ret = avfilter_graph_create_filter(&buffersrc_ctx, abuffersrc, "in",
                                       args, NULL, filter_graph);
    if (ret < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer source\n");
        goto end;
    }
    /* buffer audio sink: to terminate the filter chain. */
    ret = avfilter_graph_create_filter(&buffersink_ctx, abuffersink, "out",
                                       NULL, NULL, filter_graph);
    if (ret < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer sink\n");
        goto end;
    }
    ret = av_opt_set_int_list(buffersink_ctx, "sample_fmts", out_sample_fmts, -1,
                              AV_OPT_SEARCH_CHILDREN);
    if (ret < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot set output sample format\n");
        goto end;
    }
    ret = av_opt_set_int_list(buffersink_ctx, "channel_layouts", out_channel_layouts, -1,
                              AV_OPT_SEARCH_CHILDREN);
    if (ret < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot set output channel layout\n");
        goto end;
    }
    ret = av_opt_set_int_list(buffersink_ctx, "sample_rates", out_sample_rates, -1,
                              AV_OPT_SEARCH_CHILDREN);
    if (ret < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot set output sample rate\n");
        goto end;
    }
    /* Endpoints for the filter graph. */
    outputs->name       = av_strdup("in");
    outputs->filter_ctx = buffersrc_ctx;
    outputs->pad_idx    = 0;
    outputs->next       = NULL;
    inputs->name       = av_strdup("out");
    inputs->filter_ctx = buffersink_ctx;
    inputs->pad_idx    = 0;
    inputs->next       = NULL;
    if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
                                        &inputs, &outputs, NULL)) < 0)
        goto end;
    if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
        goto end;
    /* Print summary of the sink buffer
     * Note: args buffer is reused to store channel layout string */
    outlink = buffersink_ctx->inputs[0];
    av_get_channel_layout_string(args, sizeof(args), -1, outlink->channel_layout);
    av_log(NULL, AV_LOG_INFO, "Output: srate:%dHz fmt:%s chlayout:%s\n",
           (int)outlink->sample_rate,
           (char *)av_x_if_null(av_get_sample_fmt_name((AVSampleFormat)outlink->format), "?"),
           args);
end:
    avfilter_inout_free(&inputs);
    avfilter_inout_free(&outputs);

    return ret;
}


static void print_frame(const AVFrame *frame, FILE* dst)
{
    const int n = frame->nb_samples * av_get_channel_layout_nb_channels(av_frame_get_channel_layout(frame));
    const uint16_t *p     = (uint16_t*)frame->data[0];
    const uint16_t *p_end = p + n;
    while (p < p_end) {
        fputc(*p    & 0xff, dst);
        fputc(*p>>8 & 0xff, dst);
        p++;
    }
    fflush(dst);
}

int extractAudioFromVideo(const char* inputVideoFilename) {
    int ret;
    FILE* audioOutputStream;
    AVPacket packet0, packet;
    AVFrame *frame = av_frame_alloc();
    AVFrame *filt_frame = av_frame_alloc();
    int got_frame;

    if (!frame || !filt_frame) {
        ELOG("Could not allocate frame");
        return 1;
    }

    DLOG("Registering all codecs for processing");
    av_register_all();
    avfilter_register_all();
    DLOG("Opening %s for audio extraction", inputVideoFilename);

    ret = open_input_file(inputVideoFilename);
    if (ret == 0)
        ret = init_filters(filter_descr);

    std::string wavFilename(inputVideoFilename);
    wavFilename = wavFilename + ".wav";

    DLOG("Wriitng wav file to %s", wavFilename.c_str());
    audioOutputStream = fopen(wavFilename.c_str(), "w");

    if (audioOutputStream == NULL)
    {
        DLOG("Failed to create audio file from video %s", wavFilename.c_str());
        ret = 100;
    }

    if (ret == 0) {
        /* read all packets */
        packet0.data = NULL;
        packet.data = NULL;
        while (1) {
            if (!packet0.data) {
                if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
                    break;
                packet0 = packet;
            }
            if (packet.stream_index == audio_stream_index) {
                got_frame = 0;
                ret = avcodec_decode_audio4(dec_ctx, frame, &got_frame, &packet);
                if (ret < 0) {
                    ELOG("Error decoding audio: [%d]", ret);
                    continue;
                }
                packet.size -= ret;
                packet.data += ret;
                if (got_frame) {
                    /* push the audio data from decoded frame into the filtergraph */
                    if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, 0) < 0) {
                        ELOG("Error while feeding the audio filtergraph: [%d]", ret);
//                        av_log(NULL, AV_LOG_ERROR, "Error while feeding the audio filtergraph\n");
                        break;
                    }
                    /* pull filtered audio from the filtergraph */
                    while (1) {
                        ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
                        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
                            break;
                        if (ret < 0)
                            goto end;

                        print_frame(filt_frame, audioOutputStream);
                        av_frame_unref(filt_frame);
                    }
                }
                if (packet.size <= 0)
                    av_free_packet(&packet0);
            } else {
                /* discard non-wanted packets */
                av_free_packet(&packet0);
            }
        }
    }
end:
    avfilter_graph_free(&filter_graph);
    avcodec_close(dec_ctx);
    avformat_close_input(&fmt_ctx);
    av_frame_free(&frame);
    av_frame_free(&filt_frame);
    if (ret < 0 && ret != AVERROR_EOF) {
//        fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
        ret = 1;
    }

    return ret;
}

int main(int argc, char **argv)
{

    if (argc != 2) {
        fprintf(stderr, "Usage: %s file | %s\n", argv[0], player);
        return 1;
    }

    return extractAudioFromVideo(argv[1]);

}


#ifdef __cplusplus
}
#endif