我很困难,使用FFMpeg搜索如何从TMemoryStream(或内存中的类似缓冲区)播放视频文件.我看到很多东西,包括UltraStarDX,Delphi等昂贵的FFMpeg组件.
一个名为FFMpeg Vcl Player的组件声称从内存流播放视频格式.我下载了试用版,我猜这是使用CircularBuffer.pas(也许).
有谁知道如何做到这一点？
编辑：
现在更好的问题是如何使用FFMpeg或类似的库来播放加密的视频文件.
解决方法
要从内存流播放视频,您可以使用自定义AVIOContext.
static const int kBufferSize = 4 * 1024;
class my_iocontext_private
{
private:
my_iocontext_private(my_iocontext_private const &);
my_iocontext_private& operator = (my_iocontext_private const &);
public:
my_iocontext_private(IInputStreamPtr inputStream)
: inputStream_(inputStream),buffer_size_(kBufferSize),buffer_(static_cast<unsigned char*>(::av_malloc(buffer_size_))) {
ctx_ = ::avio_alloc_context(buffer_,buffer_size_,this,&my_iocontext_private::read,NULL,&my_iocontext_private::seek);
}
~my_iocontext_private() {
::av_free(ctx_);
::av_free(buffer_);
}
void reset_inner_context() { ctx_ = NULL; buffer_ = NULL; }
static int read(void *opaque,unsigned char *buf,int buf_size) {
my_iocontext_private* h = static_cast<my_iocontext_private*>(opaque);
return h->inputStream_->Read(buf,buf_size);
}
static int64_t seek(void *opaque,int64_t offset,int whence) {
my_iocontext_private* h = static_cast<my_iocontext_private*>(opaque);
if (0x10000 == whence)
return h->inputStream_->Size();
return h->inputStream_->Seek(offset,whence);
}
::AVIOContext *get_avio() { return ctx_; }
private:
IInputStreamPtr inputStream_; // abstract stream interface,You can adapt it to TMemoryStream
int buffer_size_;
unsigned char * buffer_;
::AVIOContext * ctx_;
};
//// ..........
/// prepare input stream:
IInputStreamPtr inputStream = MyCustomCreateInputStreamFromMemory();
my_iocontext_private priv_ctx(inputStream);
AVFormatContext * ctx = ::avformat_alloc_context();
ctx->pb = priv_ctx.get_avio();
int err = avformat_open_input(&ctx,"arbitrarytext",NULL);
if (err < 0)
return -1;
//// normal usage of ctx
//// avformat_find_stream_info(ctx,NULL);
//// av_read_frame(ctx,&pkt);
//// etc..