/// <summary>
/// 开启线程
/// </summary>
/// <param name="fileName"></param>
/// <param name="sdlVideo"></param>
public void Start(string fileName, SDLHelper sdlvideo, SDLAudio sdlAudio)
{
// 视频线程
threadVideo = new Thread(() =>
{
try
{
RunVideo(fileName, sdlvideo);
}
catch (Exception ex)
{
Console.WriteLine("JT1078CodecForMp4.Run Video", ex);
}
});
threadVideo.IsBackground = true;
threadVideo.Start();
// 音频线程
//threadAudio = new Thread(() =>
//{
// try
// {
// RunAudio(fileName, sdlAudio);
// }
// catch (Exception ex)
// {
// Console.WriteLine("JT1078CodecForMp4.Run Audio", ex);
// }
//});
//threadAudio.IsBackground = true;
//threadAudio.Start();
}
/// <summary>
/// 音频AAC转PCM并使用SDL进行播放
/// </summary>
/// <param name="fileName"></param>
/// <param name="sdlAudio"></param>
/// <returns></returns>
public unsafe int RunAudio(string fileName, SDLAudio sdlAudio)
{
IsRun = true;
exit_thread = false;
pause_thread = false;
threadAudio = Thread.CurrentThread;
int error, frame_count = 0;
int got_frame, ret;
AVFormatContext *ofmt_ctx = null;
SwsContext * pSwsCtx = null;
IntPtr convertedFrameBufferPtr = IntPtr.Zero;
try
{
// 注册编解码器
ffmpeg.avcodec_register_all();
// 获取文件信息上下文初始化
ofmt_ctx = ffmpeg.avformat_alloc_context();
// 打开媒体文件
error = ffmpeg.avformat_open_input(&ofmt_ctx, fileName, null, null);
if (error != 0)
{
throw new ApplicationException($"ffmepg avformat_open_input error: {error}");
}
// 获取流的通道
for (int i = 0; i < ofmt_ctx->nb_streams; i++)
{
if (ofmt_ctx->streams[i]->codec->codec_type == AVMediaType.AVMEDIA_TYPE_AUDIO)
{
audioindex = i;
Console.WriteLine("audio.............." + audioindex);
}
}
if (audioindex == -1)
{
Console.WriteLine("Couldn't find a audio stream.（没有找到音频流）");
return(-1);
}
// 音频流处理
if (audioindex > -1)
{
//根据索引拿到对应的流,根据流拿到解码器上下文
AVCodecContext *pCodeCtx = ofmt_ctx->streams[audioindex]->codec;
//再根据上下文拿到编解码id，通过该id拿到解码器
AVCodec *pCodec = ffmpeg.avcodec_find_decoder(pCodeCtx->codec_id);
if (pCodec == null)
{
Console.WriteLine("没有找到编码器");
return(-1);
}
//打开编码器
if (ffmpeg.avcodec_open2(pCodeCtx, pCodec, null) < 0)
{
Console.WriteLine("编码器无法打开");
return(-1);
}
Console.WriteLine("Find a audio stream. channel=" + audioindex);
//编码数据
AVPacket *packet = (AVPacket *)ffmpeg.av_malloc((ulong)(sizeof(AVPacket)));
//解压缩数据
AVFrame *frame = ffmpeg.av_frame_alloc();
//frame->16bit 44100 PCM 统一音频采样格式与采样率
SwrContext *swrCtx = ffmpeg.swr_alloc();
//重采样设置选项-----------------------------------------------------------start
//输入的采样格式
AVSampleFormat in_sample_fmt = pCodeCtx->sample_fmt;
//输出的采样格式 16bit PCM
AVSampleFormat out_sample_fmt = AVSampleFormat.AV_SAMPLE_FMT_S16;
//输入的采样率
int in_sample_rate = pCodeCtx->sample_rate;
//输出的采样率
int out_sample_rate = 44100;
//输入的声道布局
long in_ch_layout = (long)pCodeCtx->channel_layout;
//输出的声道布局
int out_ch_layout = ffmpeg.AV_CH_LAYOUT_MONO;
ffmpeg.swr_alloc_set_opts(swrCtx, out_ch_layout, out_sample_fmt, out_sample_rate, in_ch_layout, in_sample_fmt, in_sample_rate, 0, null);
ffmpeg.swr_init(swrCtx);
//重采样设置选项-----------------------------------------------------------end
//获取输出的声道个数
int out_channel_nb = ffmpeg.av_get_channel_layout_nb_channels((ulong)out_ch_layout);
//存储pcm数据
byte *out_buffer = (byte *)ffmpeg.av_malloc(2 * 44100);
//一帧一帧读取压缩的音频数据AVPacket
while (ffmpeg.av_read_frame(ofmt_ctx, packet) >= 0)
{
// 退出线程
if (exit_thread)
{
break;
}
// 暂停解析
if (pause_thread)
{
while (pause_thread)
{
Thread.Sleep(100);
}
}
if (packet->stream_index == audioindex)
{
//解码AVPacket->AVFrame
ret = ffmpeg.avcodec_decode_audio4(pCodeCtx, frame, &got_frame, packet);
if (ret < 0)
{
Console.WriteLine("音频解码失败");
return(-1);
}
// 读取帧数据
if (got_frame > 0)
{
frame_count++;
Console.WriteLine("音频帧数:第 " + frame_count + " 帧");
var data_ = frame->data;
ffmpeg.swr_convert(swrCtx, &out_buffer, 2 * 44100, (byte **)&data_, frame->nb_samples);
//获取sample的size
int out_buffer_size = ffmpeg.av_samples_get_buffer_size(null, out_channel_nb, frame->nb_samples, out_sample_fmt, 1);
//写入文件进行测试
var data = out_buffer;
sdlAudio.PlayAudio((IntPtr)data, out_buffer_size);
}
}
ffmpeg.av_free_packet(packet);
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
finally
{
if (&ofmt_ctx != null)
{
ffmpeg.avformat_close_input(&ofmt_ctx);//关闭流文件
}
}
IsRun = false;
return(0);
}
