使用FFmpeg新解码API解封装解码音视频(代码实例)

在ffmpeg的源代码中，有新旧版本的编解码接口调用示例，但是demux、mux然后decode、encode的联动起来的接口调用实例并没有，在使用旧版本的编解码接口在编译时会报接口弃用告警信息，所以最好尽快把原有的调用方式切换到新的编解码接口调用方式，告警信息如下：

liuqideMBP:xxx liuqi$ make doc/examples/demuxing_decoding
CC  doc/examples/demuxing_decoding.o
src/doc/examples/demuxing_decoding.c:73:15: warning: 'avcodec_decode_video2' is deprecated [-Wdeprecated-declarations]
        ret = avcodec_decode_video2(video_dec_ctx, frame, got_frame, &pkt);
              ^
src/libavcodec/avcodec.h:4631:1: note: 'avcodec_decode_video2' has been explicitly marked deprecated here
attribute_deprecated
^
src/libavutil/attributes.h:94:49: note: expanded from macro 'attribute_deprecated'
#    define attribute_deprecated __attribute__((deprecated))
                                                ^
src/doc/examples/demuxing_decoding.c:111:15: warning: 'avcodec_decode_audio4' is deprecated [-Wdeprecated-declarations]
        ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt);
              ^
src/libavcodec/avcodec.h:4582:1: note: 'avcodec_decode_audio4' has been explicitly marked deprecated here
attribute_deprecated
^
src/libavutil/attributes.h:94:49: note: expanded from macro 'attribute_deprecated'
#    define attribute_deprecated __attribute__((deprecated))
                                                ^
2 warnings generated.
LD  doc/examples/demuxing_decoding_g
ld: warning: directory not found for option '-Llibavresample'
STRIP   doc/examples/demuxing_decoding

为了修改方便，而网上又没有只管举例的相关完整的实例，所以在这里写一个例子，供大伙参考

/*
 * Copyright (c) 2017 bbs.chinaffmpeg.com 孙悟空
 *
 * 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
 * Demuxing and decoding example.
 *
 * Show how to use the libavformat and libavcodec API to demux and
 * decode audio and video data.
 * @example demuxing_decoding.c
 */

#include <libavutil/imgutils.h>
#include <libavutil/samplefmt.h>
#include <libavutil/timestamp.h>
#include <libavformat/avformat.h>

static AVFormatContext *fmt_ctx = NULL;
static AVCodecContext *video_dec_ctx = NULL, *audio_dec_ctx;
static int width, height;
static enum AVPixelFormat pix_fmt;
static AVStream *video_stream = NULL, *audio_stream = NULL;
static const char *src_filename = NULL;
static const char *video_dst_filename = NULL;
static const char *audio_dst_filename = NULL;
static FILE *video_dst_file = NULL;
static FILE *audio_dst_file = NULL;

static uint8_t *video_dst_data[4] = {NULL};
static int video_dst_linesize[4];
static int video_dst_bufsize;

static int video_stream_idx = -1, audio_stream_idx = -1;
static AVFrame *frame = NULL;
static AVPacket pkt;
static int video_frame_count = 0;
static int audio_frame_count = 0;

/* Enable or disable frame reference counting. You are not supposed to support
 * both paths in your application but pick the one most appropriate to your
 * needs. Look for the use of refcount in this example to see what are the
 * differences of API usage between them. */
static int refcount = 0;

static int decode_packet(int *got_frame, int cached)
{
    int ret = 0;
    int i = 0;
    int ch = 0;
    int data_size = 0;
    int decoded = pkt.size;

    *got_frame = 0;

    if (pkt.stream_index == video_stream_idx) {
        /* decode video frame */
        ret = avcodec_send_packet(video_dec_ctx, &pkt);
        if (ret < 0) {
            fprintf(stderr, "Error sending a packet for decoding\n");
            exit(1);
        }

        while (ret >= 0) {
            ret = avcodec_receive_frame(video_dec_ctx, frame);
            if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
                return ret;
            else if (ret < 0) {
                fprintf(stderr, "Error during decoding\n");
                exit(1);
            }
            printf("bbs.chinaffmpeg.com 孙悟空 video_frame%s n:%d coded_n:%d\n",
                   cached ? "(cached)" : "",
                   video_frame_count++, frame->coded_picture_number);

            /* copy decoded frame to destination buffer:
             * this is required since rawvideo expects non aligned data */
            av_image_copy(video_dst_data, video_dst_linesize,
                          (const uint8_t **)(frame->data), frame->linesize,
                          pix_fmt, width, height);

            /* write to rawvideo file */
            fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file);

            printf("saving frame %3d\n", video_dec_ctx->frame_number);
            fflush(stdout);
        }
    } else if (pkt.stream_index == audio_stream_idx) {
        /* decode audio frame */
#if 1
        /* send the packet with the compressed data to the decoder */
        ret = avcodec_send_packet(audio_dec_ctx, &pkt);
        if (ret < 0) {
            fprintf(stderr, "Error submitting the packet to the decoder\n");
            exit(1);
        }

        /* read all the output frames (in general there may be any number of them */
        while (ret >= 0) {
            ret = avcodec_receive_frame(audio_dec_ctx, frame);
            if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
                return ret;
            else if (ret < 0) {
                fprintf(stderr, "Error during decoding\n");
                exit(1);
            }
            data_size = av_get_bytes_per_sample(audio_dec_ctx->sample_fmt);
            if (data_size < 0) {
                /* This should not occur, checking just for paranoia */
                fprintf(stderr, "Failed to calculate data size\n");
                exit(1);
            }
            for (i = 0; i < frame->nb_samples; i++)
                for (ch = 0; ch < audio_dec_ctx->channels; ch++)
                    fwrite(frame->data[ch] + data_size*i, 1, data_size, audio_dst_file);
        }

        printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",
               cached ? "(cached)" : "",
               audio_frame_count++, frame->nb_samples,
               av_ts2timestr(frame->pts, &audio_dec_ctx->time_base));
#else
        ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt);
        if (ret < 0) {
            fprintf(stderr, "Error decoding audio frame (%s)\n", av_err2str(ret));
            return ret;
        }
        /* Some audio decoders decode only part of the packet, and have to be
         * called again with the remainder of the packet data.
         * Sample: 转自bbs.chinaffmpeg.com 孙悟空fate-suite/lossless-audio/
         * luckynight-partial.shn
         * Also, some decoders might over-read the packet. */
        decoded = FFMIN(ret, pkt.size);

        if (*got_frame) {
            size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);
            printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",
                   cached ? "(cached)" : "",
                   audio_frame_count++, frame->nb_samples,
                   av_ts2timestr(frame->pts, &audio_dec_ctx->time_base));

            /* Write the raw audio data samples of the first plane. This works
             * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,
             * most audio decoders output planar audio, which uses a separate
             * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).
             * In other words, this code will write only the first audio channel
             * in these cases.
             * You should use libswresample or libavfilter to convert the frame
             * to packed data. */
            fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);
        }
#endif
    }

    /* If we use frame reference counting, we own the data and need
     * to de-reference it when we don't use it anymore */
    if (*got_frame && refcount)
        av_frame_unref(frame);

    return decoded;
}

static int open_codec_context(int *stream_idx,
                              AVCodecContext **dec_ctx, AVFormatContext *fmt_ctx, enum AVMediaType type)
{
    int ret, stream_index;
    AVStream *st;
    AVCodec *dec = NULL;
    AVDictionary *opts = NULL;

    ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
    if (ret < 0) {
        fprintf(stderr, "Could not find %s stream in input file '%s'\n",
                av_get_media_type_string(type), src_filename);
        return ret;
    } else {
        stream_index = ret;
        st = fmt_ctx->streams[stream_index];

        /* find decoder for the stream */
        dec = avcodec_find_decoder(st->codecpar->codec_id);
        if (!dec) {
            fprintf(stderr, "Failed to find %s codec\n",
                    av_get_media_type_string(type));
            return AVERROR(EINVAL);
        }

        /* Allocate a codec context for the decoder */
        *dec_ctx = avcodec_alloc_context3(dec);
        if (!*dec_ctx) {
            fprintf(stderr, "Failed to allocate the %s codec context\n",
                    av_get_media_type_string(type));
            return AVERROR(ENOMEM);
        }

        /* Copy codec parameters from input stream to output codec context */
        if ((ret = avcodec_parameters_to_context(*dec_ctx, st->codecpar)) < 0) {
            fprintf(stderr, "Failed to copy %s codec parameters to decoder context\n",
                    av_get_media_type_string(type));
            return ret;
        }

        /* Init the decoders, with or without reference counting */
        av_dict_set(&opts, "refcounted_frames", refcount ? "1" : "0", 0);
        if ((ret = avcodec_open2(*dec_ctx, dec, &opts)) < 0) {
            fprintf(stderr, "Failed to open %s codec\n",
                    av_get_media_type_string(type));
            return ret;
        }
        *stream_idx = stream_index;
    }

    return 0;
}

static int get_format_from_sample_fmt(const char **fmt,
                                      enum AVSampleFormat sample_fmt)
{
    int i;
    struct sample_fmt_entry {
        enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
    } sample_fmt_entries[] = {
        { AV_SAMPLE_FMT_U8, "u8", "u8" },
        { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
        { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
        { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
        { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
    };
    *fmt = NULL;

    for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
        struct sample_fmt_entry *entry = &sample_fmt_entries[i];
        if (sample_fmt == entry->sample_fmt) {
            *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
            return 0;
        }
    }

    fprintf(stderr,
            "sample format %s is not supported as output format\n",
            av_get_sample_fmt_name(sample_fmt));
    return -1;
}

int main (int argc, char **argv)
{
    int ret = 0, got_frame;

    if (argc != 4 && argc != 5) {
        fprintf(stderr, "usage: %s [-refcount] input_file video_output_file audio_output_file\n"
                "API example program to show how to read frames from an input file.\n"
                "This program reads frames from a file, decodes them, and writes decoded\n"
                "video frames to a rawvideo file named video_output_file, and decoded\n"
                "audio frames to a rawaudio file named audio_output_file.\n\n"
                "If the -refcount option is specified, the program use the\n"
                "reference counting frame system which allows keeping a copy of\n"
                "the data for longer than one decode call.\n"
                "\n", argv[0]);
        exit(1);
    }
    if (argc == 5 && !strcmp(argv[1], "-refcount")) {
        refcount = 1;
        argv++;
    }
    src_filename = argv[1];
    video_dst_filename = argv[2];
    audio_dst_filename = argv[3];

    /* register all formats and codecs */
    av_register_all();

    /* open input file, and allocate format context */
    if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
        fprintf(stderr, "Could not open source file %s\n", src_filename);
        exit(1);
    }

    /* retrieve stream information */
    if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
        fprintf(stderr, "Could not find stream information\n");
        exit(1);
    }

    if (open_codec_context(&video_stream_idx, &video_dec_ctx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) {
        video_stream = fmt_ctx->streams[video_stream_idx];

        video_dst_file = fopen(video_dst_filename, "wb");
        if (!video_dst_file) {
            fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
            ret = 1;
            goto end;
        }

        /* allocate image where the decoded image will be put */
        width = video_dec_ctx->width;
        height = video_dec_ctx->height;
        pix_fmt = video_dec_ctx->pix_fmt;
        ret = av_image_alloc(video_dst_data, video_dst_linesize,
                             width, height, pix_fmt, 1);
        if (ret < 0) {
            fprintf(stderr, "Could not allocate raw video buffer\n");
            goto end;
        }
        video_dst_bufsize = ret;
    }

    if (open_codec_context(&audio_stream_idx, &audio_dec_ctx, fmt_ctx, AVMEDIA_TYPE_AUDIO) >= 0) {
        audio_stream = fmt_ctx->streams[audio_stream_idx];
        audio_dst_file = fopen(audio_dst_filename, "wb");
        if (!audio_dst_file) {
            fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
            ret = 1;
            goto end;
        }
    }

    /* dump input information to stderr */
    av_dump_format(fmt_ctx, 0, src_filename, 0);

    if (!audio_stream && !video_stream) {
        fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
        ret = 1;
        goto end;
    }

    frame = av_frame_alloc();
    if (!frame) {
        fprintf(stderr, "Could not allocate frame\n");
        ret = AVERROR(ENOMEM);
        goto end;
    }

    /* initialize packet, set data to NULL, let the demuxer fill it */
    av_init_packet(&pkt);
    pkt.data = NULL;
    pkt.size = 0;

    if (video_stream)
        printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
    if (audio_stream)
        printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);

    /* read frames from the file */
    while (av_read_frame(fmt_ctx, &pkt) >= 0) {
        AVPacket orig_pkt = pkt;
        do {
            ret = decode_packet(&got_frame, 0);
            if (ret < 0)
                break;
            pkt.data += ret;
            pkt.size -= ret;
        } while (pkt.size > 0);
        av_packet_unref(&orig_pkt);
    }

    /* flush cached frames */
    pkt.data = NULL;
    pkt.size = 0;
    do {
        decode_packet(&got_frame, 1);
    } while (got_frame);

    printf("Demuxing succeeded.\n");

    if (video_stream) {
        printf("Play the output video file with the command:\n"
               "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
               av_get_pix_fmt_name(pix_fmt), width, height,
               video_dst_filename);
    }

    if (audio_stream) {
        enum AVSampleFormat sfmt = audio_dec_ctx->sample_fmt;
        int n_channels = audio_dec_ctx->channels;
        const char *fmt;

        if (av_sample_fmt_is_planar(sfmt)) {
            const char *packed = av_get_sample_fmt_name(sfmt);
            printf("Warning: the sample format the decoder produced is planar "
                   "(%s). This example will output the first channel only.\n",
                   packed ? packed : "?");
            sfmt = av_get_packed_sample_fmt(sfmt);
            n_channels = 2;
        }

        if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)
            goto end;

        printf("Play the output audio file with the command:\n"
               "ffplay -f %s -ac %d -ar %d %s\n",
               fmt, n_channels, audio_dec_ctx->sample_rate,
               audio_dst_filename);
    }

end:
    avcodec_free_context(&video_dec_ctx);
    avcodec_free_context(&audio_dec_ctx);
    avformat_close_input(&fmt_ctx);
    if (video_dst_file)
        fclose(video_dst_file);
    if (audio_dst_file)
        fclose(audio_dst_file);
    av_frame_free(&frame);
    av_free(video_dst_data[0]);

    return ret < 0;
}

下面看一下编译的方式，其实我是用的ffmpeg原生的编译方式编译的make doc/examples/demuxing_decoding，在这里贴一下make -n doc/examples/demuxing_decoding的输出

liuqideMBP:xxx liuqi$ make -n doc/examples/demuxing_decoding
printf "CC\t%s\n" doc/examples/demuxing_decoding.o; ccache gcc -I. -Isrc/ -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -I/Users/liuqi/multimedia/ffmpeg/compat/dispatch_semaphore -DPIC -DZLIB_CONST -std=c11 -Werror=partial-availability -fomit-frame-pointer -fPIC -pthread -I/usr/local/include -I/usr/local/Cellar/fontconfig/2.12.6/include -I/usr/local/opt/freetype/include/freetype2 -I/usr/local/Cellar/fribidi/0.19.7_1/include/fribidi -I/usr/local/Cellar/glib/2.54.2/include/glib-2.0 -I/usr/local/Cellar/glib/2.54.2/lib/glib-2.0/include -I/usr/local/opt/gettext/include -I/usr/local/Cellar/pcre/8.41/include -I/usr/local/opt/freetype/include/freetype2 -I/usr/local/Cellar/libbluray/1.0.1/include -I/usr/local/include -I/usr/local/Cellar/fontconfig/2.12.6/include -I/usr/local/opt/freetype/include/freetype2 -I/usr/local/opt/freetype/include/freetype2 -I/usr/local/Cellar/speex/1.2rc1/include -I/usr/local/include -I/usr/local/Cellar/x265/2.5_1/include -g -Wdeclaration-after-statement -Wall -Wdisabled-optimization -Wpointer-arith -Wredundant-decls -Wwrite-strings -Wtype-limits -Wundef -Wmissing-prototypes -Wno-pointer-to-int-cast -Wstrict-prototypes -Wempty-body -Wno-parentheses -Wno-switch -Wno-format-zero-length -Wno-pointer-sign -Wno-unused-const-variable -O3 -fno-math-errno -fno-signed-zeros -mstack-alignment=16 -Qunused-arguments -Werror=implicit-function-declaration -Werror=missing-prototypes -Werror=return-type -D_THREAD_SAFE -I/usr/local/include/SDL2 -MMD -MF doc/examples/demuxing_decoding.d -MT doc/examples/demuxing_decoding.o -c -o doc/examples/demuxing_decoding.o src/doc/examples/demuxing_decoding.c
printf "LD\t%s\n" doc/examples/demuxing_decoding_g; ccache gcc -Llibavcodec -Llibavdevice -Llibavfilter -Llibavformat -Llibavresample -Llibavutil -Llibpostproc -Llibswscale -Llibswresample -Wl,-dynamic,-search_paths_first -Qunused-arguments -o doc/examples/demuxing_decoding_g doc/examples/demuxing_decoding.o -lavdevice -lavfilter -lavformat -lavcodec -lpostproc -lswresample -lswscale -lavutil -framework Foundation -lm -framework AVFoundation -framework CoreVideo -framework CoreMedia -pthread -framework CoreGraphics -L/usr/local/lib -lSDL2 -framework OpenGL -framework OpenGL -pthread -lm -L/usr/local/lib -lass -framework CoreImage -framework AppKit -L/usr/local/Cellar/fontconfig/2.12.6/lib -L/usr/local/opt/freetype/lib -lfontconfig -lfreetype -L/usr/local/opt/freetype/lib -lfreetype -lm -lbz2 -L/usr/local/Cellar/libbluray/1.0.1/lib -lbluray -lz -Wl,-framework,CoreFoundation -Wl,-framework,Security -liconv -lm -llzma -lz -framework AudioToolbox -L/usr/local/lib -lfdk-aac -lmp3lame -L/usr/local/Cellar/speex/1.2rc1/lib -lspeex -L/usr/local/lib -lx264 -L/usr/local/Cellar/x265/2.5_1/lib -lx265 -pthread -framework VideoToolbox -framework CoreFoundation -framework CoreMedia -framework CoreVideo -framework CoreServices -lm -lm -lm -pthread -lm -framework VideoToolbox -framework CoreFoundation -framework CoreMedia -framework CoreVideo -framework CoreServices
printf "STRIP\t%s\n" doc/examples/demuxing_decoding; strip -x -o doc/examples/demuxing_decoding doc/examples/demuxing_decoding_g