On Thu, 20 Jan 2005, Steven Boswell II wrote: > Eh? It was my understanding that the lines of the > top field were stored at even y indices, and the > lines of the bottom field were stored at odd y > indices, in the YCbCr data returned by > y4m_read_frame(). The code for y4m_read_fields() > certainly suggests that too. Which means I don't > see how interpreting the data as a frame or as two > fields changes the storage format of chroma or > anything else.
If you have a progressive frame in 4:2:0, then the first chroma line is the average from lines 1 and 2. The second chroma line is the average of 3 and 4. If you have an interlaced frame, the first chroma line is the average of the first two lines of the first field. With the fields interleaved, they are lines 1 and 3. The second choroma line is from the first two lines of the second field, which are lines 2 and 4. Assuming top field first. ------------------------------------------------------- This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting Tool for open source databases. Create drag-&-drop reports. Save time by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc. Download a FREE copy at http://www.intelliview.com/go/osdn_nl _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
