public MediaStream(Stream baseStream, bool write = false, AVOutputFormat *outputFormat = null)
{
if (write && !baseStream.CanWrite)
{
throw new ArgumentException($"流不能被写入，请确保Stream.CanWrite为true");
}
if (baseStream.CanRead)
{
procRead = Read;
}
if (write && baseStream.CanWrite)
{
procWrite = Write;
}
if (baseStream.CanSeek)
{
procSeek = Seek;
}
this.baseStream = baseStream;
try {
formatContext = FF.avformat_alloc_context();
var buffer = (byte *)FF.av_malloc((IntPtr)bufferLength);
ioContext = FF.avio_alloc_context(buffer, bufferLength, write, null, procRead, procWrite, procSeek);
if (write)
{
formatContext->Oformat = outputFormat;
}
formatContext->Pb = ioContext;
} catch {
Dispose();
throw;
}
}
public IOContext(Stream stream, bool writable = false)
{
this.stream = stream ?? throw new ArgumentNullException(nameof(stream));
ulong paddingLength = writable ? 0ul : ffmpeg.AV_INPUT_BUFFER_PADDING_SIZE; // reversed
// note: this can be replaced...
var buffer = (byte *)ffmpeg.av_malloc(bufferSize + paddingLength);
// reference to prevent garbage collection
read = Read;
write = Write;
seek = Seek;
Pointer = ffmpeg.avio_alloc_context(
buffer: buffer,
buffer_size: bufferSize,
write_flag: writable ? 1 : 0,
opaque: null,
read_packet: read,
write_packet: write,
seek: seek
);
Pointer->seekable = ffmpeg.AVIO_SEEKABLE_NORMAL; // | ffmpeg.AVIO_SEEKABLE_TIME;
}
public AVIOStream(Stream stream, FileAccess access)
{
this.stream = stream;
Access = access;
if (CanRead && !stream.CanRead)
{
throw new ArgumentException("Can't read from stream");
}
if (CanWrite && !stream.CanWrite)
{
throw new ArgumentException("Can't write to stream");
}
byte *ioBuffer = (byte *)ffmpeg.av_malloc(DefaultBufferSize);
if (ioBuffer == null)
{
throw new FFmpegException(ffmpeg.AVERROR(ffmpeg.ENOMEM), "Failed to allocate I/O buffer");
}
int writeFlag = 0;
avio_alloc_context_read_packet readPacket = null;
avio_alloc_context_write_packet writePacket = null;
if (CanWrite)
{
writeFlag = 1;
writePacket = WritePacket;
writePacketCallbackHandle = GCHandle.Alloc(writePacket);
}
if (CanRead)
{
readPacket = ReadPacket;
readPacketCallbackHandle = GCHandle.Alloc(readPacket);
}
ioContext = ffmpeg.avio_alloc_context(ioBuffer, (int)DefaultBufferSize, writeFlag, null, readPacket, writePacket, null);
if (ioContext == null)
{
ffmpeg.av_free(ioBuffer);
throw new FFmpegException(ffmpeg.AVERROR(ffmpeg.ENOMEM), "Failed to allocate I/O context");
}
}