Michael Niedermayer <michaelni@gmx.at> writes:
On Tue, Feb 19, 2008 at 08:19:39PM +0000, Måns Rullgård wrote:
Michael Niedermayer <michaelni@gmx.at> writes:
+transmit_ts (t) + The timestamp at which the first bit of the syncpoint is transmitted.
In MPEG-TS, the PCR value is the time of arrival of the last bit (actually the byte containing the last bit). This could be seen as more logical, as then no timestamp will refer to a time in the past. I doubt the distinction is relevant in practice, but I wanted to point it out nonetheless.
Last bit of what? The transmit_ts or the syncpoint? A well written demuxer/receiver will check the crc of the syncpoint before using transmit_ts thus it would still be in the past if its the last bit of transmit_ts. Also either way transmit_ts is variable length and that would slightly complicate setting it exactly to the time of the last bit.
First bit is fine. As I said, I only mentioned this since it is a difference from MPEG TS.
+ MUST be less than or equal to all following dts.
I'm not happy with this. It allows the clock to reach the DTS of a frame before the frame has arrived. Placing restrictions on the transmit_ts value is not sufficient to avoid this condition. Instead, it must be a rule that a frame must be completely received before the reference clock reaches its DTS value.
What about:
transmit_ts (t) The value of the reference clock at the moment when the first bit of transmit_ts is transmitted/received. The reference clock MUST always be less than or equal to the DTS of every not yet completely received frame.
Much better. -- Måns Rullgård mans@mansr.com