delphi – 从MemoryStream播放视频,使用FFMpeg

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..

delphi – 从MemoryStream播放视频,使用FFMpeg

解决方法

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