基于Qt编写全能播放组件的示例代码

//通过avcode版本定义对应主版本
#if (LIBAVCODEC_VERSION_MAJOR == 56)
#define FFMPEG_VERSION_MAJOR 2
#elif (LIBAVCODEC_VERSION_MAJOR == 57)
#define FFMPEG_VERSION_MAJOR 3
#elif (LIBAVCODEC_VERSION_MAJOR == 58)
#define FFMPEG_VERSION_MAJOR 4
#elif (LIBAVCODEC_VERSION_MAJOR == 59)
#define FFMPEG_VERSION_MAJOR 5
#elif (LIBAVCODEC_VERSION_MAJOR == 60)
#define FFMPEG_VERSION_MAJOR 6
#endif
int FFmpegHelper::getRotate(AVStream *stream)
{
    int rotate = 0;
    //测试发现ffmpeg2不支持旋转滤镜
#if (FFMPEG_VERSION_MAJOR < 3)
    return rotate;
#endif
#if (FFMPEG_VERSION_MAJOR < 5)
    AVDictionaryEntry *tag = NULL;
    tag = av_dict_get(stream->metadata, "rotate", NULL, 0);
    if (tag) {
        rotate = atoi(tag->value);
    }
#else
    //从ffplay源码中找到的方法
    double theta = 0;
    quint8 *displaymatrix = av_stream_get_side_data(stream, AV_PKT_DATA_DISPLAYMATRIX, NULL);
    if (displaymatrix) {
        theta = -av_display_rotation_get((qint32 *) displaymatrix);
        theta -= 360 * floor(theta / 360 + 0.9 / 360);
        rotate = theta;
    }
#endif
    return rotate;
}
void FFmpegHelper::setRotate(AVStream *stream, int rotate)
{
#if (FFMPEG_VERSION_MAJOR < 5)
    av_dict_set(&stream->metadata, "rotate", QString::number(rotate).toUtf8().constData(), 0);
#else
    quint8 *sidedata = av_stream_new_side_data(stream, AV_PKT_DATA_DISPLAYMATRIX, sizeof(qint32) * 9);
    if (sidedata) {
        av_display_rotation_set((qint32 *)sidedata, rotate);
    }
#endif
}
void FFmpegHelper::getStreamInfo(AVStream *stream, int &id, int &width, int &height, qint64 &bitrate, int &sampleRate, int &channelCount, int &profile)
{
#if (FFMPEG_VERSION_MAJOR < 3)
    id = stream->codec->codec_id;
    width = stream->codec->width;
    height = stream->codec->height;
    bitrate = stream->codec->bit_rate;
    sampleRate = stream->codec->sample_rate;
    channelCount = stream->codec->channels;
    profile = stream->codec->profile;
#else
    id = stream->codecpar->codec_id;
    width = stream->codecpar->width;
    height = stream->codecpar->height;
    bitrate = stream->codecpar->bit_rate;
    sampleRate = stream->codecpar->sample_rate;
    channelCount = stream->codecpar->channels;
    profile = stream->codecpar->profile;
#endif
}
int FFmpegHelper::copyContext(AVStream *streamIn, AVStream *streamOut)
{
    int result = -1;
    //设置 codec_tag = 0 这个很关键(不加保存的数据可能不正确)
#if (FFMPEG_VERSION_MAJOR < 3)
    result = avcodec_copy_context(streamOut->codec, streamIn->codec);
    streamOut->codec->codec_tag = 0;
#else
    result = avcodec_parameters_copy(streamOut->codecpar, streamIn->codecpar);
    streamOut->codecpar->codec_tag = 0;
#endif
    return result;
}
int FFmpegHelper::copyContext(AVCodecContext *avctx, AVStream *stream, bool from)
{
    int result = -1;
#if (FFMPEG_VERSION_MAJOR < 3)
    if (from) {
        result = avcodec_copy_context(stream->codec, avctx);
    } else {
        result = avcodec_copy_context(avctx, stream->codec);
    }
#else
    if (from) {
        result = avcodec_parameters_from_context(stream->codecpar, avctx);
    } else {
        result = avcodec_parameters_to_context(avctx, stream->codecpar);
    }
#endif
    return result;
}
int FFmpegHelper::decode(FFmpegThread *thread, AVCodecContext *avctx, AVPacket *packet, AVFrame *frame, bool video)
{
    int result = -1;
#ifdef videoffmpeg
    QString flag = video ? "视频解码" : "音频解码";
#if (FFMPEG_VERSION_MAJOR < 3)
    if (video) {
        avcodec_decode_video2(avctx, frame, &result, packet);
        if (result < 0) {
            thread->debug(result, flag, "avcodec_decode_video2");
            return result;
        }
    } else {
        avcodec_decode_audio4(avctx, frame, &result, packet);
        if (result < 0) {
            thread->debug(result, flag, "avcodec_decode_audio4");
            return result;
        }
    }
    goto end;
#else
    result = avcodec_send_packet(avctx, packet);
    if (result < 0 && (result != AVERROR(EAGAIN)) && (result != AVERROR_EOF)) {
        //if (result < 0) {
        thread->debug(result, flag, "avcodec_send_packet");
        return result;
    }
    while (result >= 0) {
        result = avcodec_receive_frame(avctx, frame);
        if (result == AVERROR(EAGAIN) || result == AVERROR_EOF) {
            break;
        } else if (result < 0) {
            thread->debug(result, flag, "avcodec_receive_frame");
            break;
        }
        goto end;
    }
#endif
    return result;
end:
    //调用线程处理解码后的数据
    if (video) {
        thread->decodeVideo2(packet);
    } else {
        thread->decodeAudio2(packet);
    }
#endif
    return result;
}
int FFmpegHelper::encode(FFmpegSave *thread, AVCodecContext *avctx, AVPacket *packet, AVFrame *frame, bool video)
{
    int result = -1;
#ifdef videosave
    QString flag = video ? "视频编码" : "音频编码";
#if (FFMPEG_VERSION_MAJOR < 3)
    if (video) {
        avcodec_encode_video2(avctx, packet, frame, &result);
        if (result < 0) {
            thread->debug(result, flag, "avcodec_encode_video2");
            return result;
        }
    } else {
        avcodec_encode_audio2(avctx, packet, frame, &result);
        if (result < 0) {
            thread->debug(result, flag, "avcodec_encode_audio2");
            return result;
        }
    }
    goto end;
#else
    result = avcodec_send_frame(avctx, frame);
    if (result < 0) {
        thread->debug(result, flag, "avcodec_send_frame");
        return result;
    }
    while (result >= 0) {
        result = avcodec_receive_packet(avctx, packet);
        if (result == AVERROR(EAGAIN) || result == AVERROR_EOF) {
            break;
        } else if (result < 0) {
            thread->debug(result, flag, "avcodec_receive_packet");
            break;
        }
        goto end;
    }
#endif
    return result;
end:
    thread->writePacket2(packet, video);
#endif
    return result;
}