Arguments

Description

This function callback prototype, provided by the client of the demux API, is called from the demux code. The function is only called when filtering on ae TS feed has been enabled using the start_filtering function at the dmx_demux. Any TS packets that match the filter settings are copied to a circular buffer. The filtered TS packets are delivered to the client using this callback function. The size of the circular buffer is controlled by the circular_buffer_size parameter of the dmx_ts_feed.set function. It is expected that the buffer1 and buffer2 callback parameters point to addresses within the circular buffer, but other implementations are also possible. Note that the called party should not try to free the memory the buffer1 and buffer2 parameters point to.

When this function is called, the buffer1 parameter typically points to the start of the first undelivered TS packet within a circular buffer. The buffer2 buffer parameter is normally NULL, except when the received TS packets have crossed the last address of the circular buffer and ”wrapped” to the beginning of the buffer. In the latter case the buffer1 parameter would contain an address within the circular buffer, while the buffer2 parameter would contain the first address of the circular buffer. The number of bytes delivered with this function (i.e. buffer1_length + buffer2_length) is usually equal to the value of callback_length parameter given in the set function, with one exception: if a timeout occurs before receiving callback_length bytes of TS data, any undelivered packets are immediately delivered to the client by calling this function. The timeout duration is controlled by the set function in the TS Feed API.

If a TS packet is received with errors that could not be fixed by the TS-level forward error correction (FEC), the Transport_error_indicator flag of the TS packet header should be set. The TS packet should not be discarded, as the error can possibly be corrected by a higher layer protocol. If the called party is slow in processing the callback, it is possible that the circular buffer eventually fills up. If this happens, the demux driver should discard any TS packets received while the buffer is full and return -EOVERFLOW.

The type of data returned to the callback can be selected by the dmx_ts_feed.set function. The type parameter decides if the raw TS packet (TS_PACKET) or just the payload (TS_PACKET|TS_PAYLOAD_ONLY) should be returned. If additionally the TS_DECODER bit is set the stream will also be sent to the hardware MPEG decoder.

Return

0, on success; -EOVERFLOW, on buffer overflow.