Problem with libvlc_media_new_callbacks

Gvv · Postby **Gvv** » 09 Aug 2015 14:07

I'm use libvlc with Delphi XE2.
When I loaded video via libvlc_media_new_path it play fine. Then I'm trying to use libvlc_media_new_callbacks.

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type
  unsigned_char             = Byte;
  p_unsigned_char           = PByte;
  uint64_t                  = UInt64;
  puint64_t                 = PUInt64;
  size_t                    = NativeUInt;
  ssize_t                   = NativeInt;
  PStream                   = ^TStream;
  
libvlc_media_open_cb = function(opaque: Pointer; var datap: Pointer; sizep: puint64_t): integer; cdecl;
libvlc_media_read_cb = function(opaque: Pointer; buf: p_unsigned_char; len: size_t): ssize_t; cdecl;
libvlc_media_seek_cb = function(opaque: Pointer; offset: uint64_t): integer; cdecl;
libvlc_media_close_cb = function(opaque: Pointer): integer; cdecl;
libvlc_media_new_callbacks         : function(p_instance : Plibvlc_instance_t; open_cb: libvlc_media_open_cb; read_cb: libvlc_media_read_cb; seek_cb: libvlc_media_seek_cb; close_cb: libvlc_media_close_cb; opaque: Pointer): Plibvlc_media_t; stdcall;

var
  stream: TStream;
  stream_ptr: Pointer;
  
procedure TVLC.SetMedia(mediaFile: string);
begin
  try
    // create new vlc instance
    _vlcInstance := libvlc_new(0, nil);

    //      vlcMedia := libvlc_media_new_path(_vlcInstance, PAnsiChar(AnsiString(mediaFile)));
      stream := TFileStream.Create(mediaFile, fmOpenRead);
      stream.Position := 0;
      stream_ptr := PStream(@stream);

      vlcMedia := libvlc_media_new_callbacks(_vlcInstance, MediaOpen, MediaRead, nil, MediaClose, stream_ptr);

      // create new vlc media player
      _vlcMediaPlayer := libvlc_media_player_new_from_media(vlcMedia);
  finally
    libvlc_media_release(vlcMedia);
  end;
end;
  
function MediaOpen(opaque: Pointer; var datap: Pointer; sizep: puint64_t): integer;
begin
   sizep^ := UInt64(106532864); //filesize
   Result := 0;
end;

function MediaRead(opaque: Pointer; buf: p_unsigned_char; len: size_t): ssize_t;
begin
  try
    Result := TStream(opaque^).Read(buf^, len);
  except 
    on E: Exception do Result := -1;
end;

function MediaClose(opaque: Pointer): integer;
begin
  FreeAndNil(TStream(opaque1));
end;

And video don't play. I see black screen and sound like fast rewind.

Then I'm trying to do it in C++.
I'm get example of WxWidgets Player from WIKI http://git.videolan.org/?p=vlc.git;a=bl ... k_player.c
Compile with CodeLite and MinGW, the video play fine.
I made some changes:
in open file

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        media_file = new ifstream(openFileDialog.GetPath(), ios::in|ios::binary|ios::ate);
        media_file->seekg(0, media_file->beg);
        media = libvlc_media_new_callbacks(
            vlc_inst,
            media_open_cb,
            media_read_cb,
            NULL,
            media_close_cb,
            media_file);
        libvlc_media_player_set_media(media_player, media);
        play();
        libvlc_media_release(media);

and add callback implementation:

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int media_open_cb(void *opaque, void **datap, uint64_t *sizep) {
  *sizep = 106532864;
  *datap = opaque;
   return 0;  
}    

ssize_t media_read_cb(void *opaque, unsigned char *buf, size_t len) {
    ifstream *file = (ifstream *)(opaque);
    file->read((char *)(buf), len);
    return file->gcount();
}    

void media_close_cb(void *opaque) {
    ifstream *file = (ifstream *)(opaque);
    file->close();
}

And get the same result as with Delphi XE.
What i'm doing wrong?

Postby **Rémi Denis-Courmont** » 09 Aug 2015 14:28

You forgot the seek callback.

Gvv · Postby **Gvv** » 09 Aug 2015 14:52

Thank you, implementation of seek callback solved my problem.

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