search for: y_stride

hi all, i'm trying to code a tool to get some images from a ogg/theora file .... so basically i need to get a frame and convert to rgb ... and here is my question (sorry, i'm newbe here) ... how to convert a yuv_buffer to a rgb matrix ? i tryied diferent ways but my mistakes are bassically cause i don't understant how yuv_buffer structure works ... anybody can help? thanks a lot.

..., and doing a whole lot of guessing. In the meantime, could you either confirm or deny the following guesses? 1) Before compressing with Theora, I must unpack my YUY2 data into three separate arrays (Y, U, and V respectively), and record in a "yuv_buffer" structure. 2) "yuv_buffer.y_stride" is this the number of bytes in one row of Y data. In other words, y_stride*8/y_width = num bits per Y component 3) "theora_encode_header" must be called exactly once, and its output must be the first packet received by a Theora decoder 4) "theora_encode_comment" need ne...

...width is the size of the frame and width is the size of the picture inside the frame. So now i'm completely confused. Could someone please clarify if the following is correct... theorainfo.frame_width = width of the inner picture region theorainfo.width = width of the outer frame yuvbuffer.y_stride = theorainfo.width = width of the outer frame yuvbuffer.y_width = theorainfo.frame_width = width of the inner picture region ??? Cheers, Zen.

Hi, is there any place where the possible values for the strides in the yuv_buffer structure is specified? or just in the source code? ;) I could compress a video with, lets say, yuvbuf.y_stride = yuvbuf.y_width, so the yuvbuf.y[0] really started in the start of the y channel data. I watched the video in several players, and everythings' ok. But, when programming the decompress process, the strides were negative, and, so, yuvbuf.y[0] indicated the end of the y channel data. Is this tru...

...u[cc]-128); frame[cc*4+3]=255; //R = Y + 1.371(CR - 128) //G = Y - 0.698(CR - 128) - 0.336(CB - 128) //B = Y + 1.732(CB - 128) //A = 255 } But it seems to me that this code is incorrect, because don't use y_stride, uv_height, uv_width, uv_stride fields. File libtheora-1.0alpha4.pdf doesn't contain enough useful information concerning these fields: y_stride, uv_height, uv_width, uv_stride. Please, write an example-code for needeed YCbCr to RGB convertion or give me link where wrote about that. Thanks!...

...ere I get hung up. To pass the YUV data to the various encode functions I have to create a yuv_buffer struct and set the widths, heights, and strides correctly. What I've been trying to use is: yuv_buffer yuv; yuv.y_width = Width; yuv.y_height = Height; yuv.y_stride = Width; yuv.uv_width = Width; yuv.uv_height = Height; yuv.uv_stride = Width; yuv.y = YDATA; yuv.u = UDATA; yuv.v = VDATA; There isn't a lot of documentation on how Theora "wants" the pixel data in theora.h, so...

...? 2. Getting said plugin to work was basically possible only because I'm good at using emacs copying functions, using your code for clipping+offset. I couldn't really understand why it worked, because there was one relevant concept which I simply can't understand -- stride. There's y_stride and uv_stride. Everything works now, but I'd rather understand _why_ it works, so if someone could explain what stride is (from a little googling it seems to be a concept which exists in most YUV codecs), I'd be very greatful. Other stuff: I was talking to meu on #theora about the aspect v...

Just trying to debug my theora encoder... just wondering if someone could give me some insight on a few thigns... In the yuv_buffer i'm sending in... i am just setting y_stride = y_width = videoWidth uv_stride = videoWidth/2 y_height = videoHeight uv_height = videoHeight/2 Making the y buffer (width*height) and each of u and v (width*height/4) Am i correct in doing this ? I knwo stride needn't equal width... but from the videos width, can i just make them equal ? An...

..._encode_init(&enc_state,&ti); theora_info_clear(&ti); } __declspec (dllexport) encode(signed char *yuvframe, ogg_page *op) { while (ogg_stream_pageout(&enc_stream, op) == 0) { yuv_buffer yuv_enc; yuv_enc.y_width=enc_width; yuv_enc.y_height=enc_height; yuv_enc.y_stride=enc_width; yuv_enc.uv_width=enc_width/2; yuv_enc.uv_height=enc_height/2; yuv_enc.uv_stride=enc_width/2; yuv_enc.y=yuvframe; yuv_enc.u=yuvframe+enc_width*enc_height; yuv_enc.v=yuvframe+enc_width*enc_height*5/4; theora_encode_YUVin(&enc_state,&yuv_enc); ogg...

I posted this the other day... but it didn't get delivered... ------------------------------------------------------------------- I'm getting stuck into a theora decoder for directshow... i was just wondering if someone could give me some info. What output format does theora use ? http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwmt/html/YUVFormats.asp

...code_frame(); dimension2d<s32> texDim = texture->getSize(); long* texMem = (long*) texture->lock(); for (int y=0; y<texDim.Height; ++y) { for (int x=0; x<texDim.Width; ++x) { int Y = yuvBuffer.y [y*yuvBuffer.y_stride + x]; int U = yuvBuffer.u [(y/2)*yuvBuffer.uv_stride + (x/2)]; int V = yuvBuffer.v [(y/2)*yuvBuffer.uv_stride + (x/2)]; int B = (int)(1.164*(Y - 16) + 2.018*(U - 128)); int G = (int)(1.164*(Y - 16) - 0.813*(V - 128)...

...= 1; int video_r = 320000; int video_q = 16; int frame_counter = 250; signed char *yuvframe; int fetch_video_page( ogg_page *videopage, ogg_stream_state *to, theora_state *td ) { yuv_buffer yuv; ogg_packet op; yuv.y_width = video_x; yuv.y_height = video_y; yuv.y_stride = video_x; yuv.uv_width = video_x / 2; yuv.uv_height = video_y / 2; yuv.uv_stride = video_x / 2; yuv.y = yuvframe; yuv.u = yuvframe + video_x * video_y; yuv.v = yuvframe + video_x * video_y * 5 / 4; /* is there a video page flushed? If not, work until there is. */ w...

...oY - FRAME_HEIGHT ) / 2 ) & ~1; ucYUVframe = malloc( iVideoX * iVideoY * 3 / 2 ); if( ucYUVframe == NULL ) { fprintf( stderr, "### malloc() error \n" ); return -1; } tYUVbuffer.y_width = iVideoX; tYUVbuffer.y_height = iVideoY; tYUVbuffer.y_stride = iVideoX; tYUVbuffer.uv_width = iVideoX / 2; tYUVbuffer.uv_height = iVideoY / 2; tYUVbuffer.uv_stride = iVideoX / 2; tYUVbuffer.y = ucYUVframe; tYUVbuffer.u = ucYUVframe + iVideoX * iVideoY; tYUVbuffer.v = ucYUVframe + iVideoX * iVideoY * 5 / 4; return 0; } int OGG...