Play a Video from MemoryStream, Using FFMpeg

问题:

I'm having a hard time, searching how to play a video file from a TMemoryStream (or a similar buffer in memory) using FFMpeg. I've seen many things, including UltraStarDX, expensive FFMpeg components for Delphi and so on.

One component called FFMpeg Vcl Player claims to play video formats from a memory stream. I downloaded the trial version and I guess it uses CircularBuffer.pas for that matter (maybe).

Does any one know how to do this?

Edit: Now the better question is how to play an encrypted video file, using FFMpeg or similar libraries.

回答1:

To play video from memory stream, you can use custom 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_, 0, 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, NULL);
   if (err < 0) 
       return -1;

   //// normal usage of ctx
   //// avformat_find_stream_info(ctx, NULL);
   //// av_read_frame(ctx, &pkt); 
   //// etc..

回答2:

You can waste your time rewriting FFMPEG from C++ to Delphi, or mess with wrapper libraries.

Or if you're just interested in playing a video in Delphi, then check out Mitov's VideoLab components.

http://www.mitov.com/products/videolab#components

回答3:

If you want play Stream from memory you can make a virtual memory. I suggest BoxedAppSdk.

This will help you to make a virtual drive with virtual files that you can write on it and then give the virtual path to the player component that you have.

BoxedApp is not free but it is really awesome and very simple in use!