public void Build()
{
var streams = new AVStream *[2];
var stream_dic = new Dictionary <MediaStreamType, int>();
ValidateArguments();
// open output iocontext
using var output = new IOContext(OutputPath, ffmpeg.AVIO_FLAG_WRITE);
// open muxer
using var muxer = new MediaMuxer(output, OutputExtension, OutputMimeType);
// create output streams
var firstSource = _sources.First();
AddOutputStreams(firstSource, muxer, out var vidOutStream, out var audioOutStream, out var streamMap);
// write headers
muxer.WriteHeader();
// concat media files
var context = new ConcatContext
{
Output = output,
Muxer = muxer,
VideoOutStream = vidOutStream,
AudioOutStream = audioOutStream,
StreamMap = streamMap,
};
foreach (var source in _sources)
{
ConcatFile(source, context);
}
// write trailer
muxer.WriteTrailer();
}
private void ConcatFile(Uri source, ConcatContext context)
{
using var videoDecoder = new MediaDecoder(source, HardwareDevice);
using var audioDecoder = new MediaDecoder(source, HardwareDevice);
var hasVideo = new Reference <bool>(videoDecoder.SelectStream(AVMediaType.AVMEDIA_TYPE_VIDEO));
var hasAudio = new Reference <bool>(audioDecoder.SelectStream(AVMediaType.AVMEDIA_TYPE_AUDIO));
var audioDts = new Reference <long>();
var videoDts = new Reference <long>();
while (hasVideo || hasAudio)
{
MediaStreamType type;
if (!hasAudio)
{
type = MediaStreamType.Video;
}
else if (!hasVideo)
{
type = MediaStreamType.Audio;
}
else
{
type = audioDts.Value < videoDts.Value ? MediaStreamType.Audio : MediaStreamType.Video;
}
AVStream * outStream;
MediaDecoder decoder;
Reference <long> dts;
Reference <bool> has;
switch (type)
{
case MediaStreamType.Audio:
outStream = context.AudioOutStream;
decoder = audioDecoder;
dts = audioDts;
has = hasAudio;
break;
case MediaStreamType.Video:
outStream = context.VideoOutStream;
decoder = videoDecoder;
dts = videoDts;
has = hasVideo;
break;
default:
throw new NotSupportedException();
}
using var packet = decoder.ReadPacket();
if (packet == null)
{
has.Value = false;
continue;
}
var pck = packet.Pointer;
ffmpeg.av_packet_rescale_ts(pck, decoder.TimeBase, outStream->time_base);
pck->stream_index = context.StreamMap[type];
dts.Value = pck->dts;
context.Muxer.WritePacket(pck);
}
}
