[FFmpeg-devel] [PATCH 1/1] avformat: Add alignment mode to Pro-MPEG

[Andreas Håkon]

Hi,

The Pro-MPEG FEC module has troubles with some receivers.
This patch fixes this problem incorporating the option for selecting different alignment modes.

The problem is related to the alignment of the COLUMN FEC packets (aka. when send the packet).
Current block-alignment implies a delay of quasi-the-length of the matrix size.
Then several receivers discard the column fec packets when they start to receive DATA packets from the next matrix.

Three different modes are possible (only two implemented):

- Mode 0: No alignment. When a new row starts, and the column is complete, then send the COL FEC packet. This is the default behaviour for several devices. However, this mode is prone to errors when they happen in the last row; but it's still more compatible.

- Mode 1: COL alignment. This is the default and already implemented alignment. COL FEC packets are send equispaced when processing the next matrix. Implies more delay in the receiver and a double-size buffer.

- Mode 2: ROW alignment. This is unimplemented. After compute each column it's send the COL FEC packet. Very similar to mode 0.

Please, review the code. I do several tests with professional equipment. Results improves using mode 0 with some receivers.

A.H.
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