anyone who can explain more on the difference between segment.abs_rate and segment.abs_applied_rate

[Wim Taymans]

On 10/19/2011 05:16 AM, bcxa sz wrote:
> And I also found the explanation from gst_event_new_new_segment_full():
> =====================================================
> * The @applied_rate value provides information about any rate adjustment that
> * has already been made to the timestamps and content on the buffers of the
>   * stream. (@rate * @applied_rate) should always equal the rate that has been
>   * requested for playback. For example, if an element has an input segment
>   * with intended playback @rate of 2.0 and applied_rate of 1.0, it can adjust
>   * incoming timestamps and buffer content by half and output a newsegment event
>   * with @rate of 1.0 and @applied_rate of 2.0
> ---------------------------------------------------------------------------------------------
>
> Can someone explain how and why the rate and applied_rate is changed
> in above use case?

The easiest way to understand this is to take a piece of paper and write 
down some timestamps and newsegment event values and then calculate the 
stream time and running time of the timestamps.

The rate scales the running time so that playback is slower/faster.

The applied rate scales the stream time so that reported playback time 
is slower/faster.

Wim

>
> On Wed, Oct 19, 2011 at 10:14 AM, bcxa sz<bcxa.sz at gmail.com>  wrote:
>> Hi Developers,
>>
>> I am reading the design document on the sync and notice formulas to
>> calculate the running time and the stream time:
>>
>> B.running_time = (B.time_stamp - NS.start) / NS.abs_rate + NS.accum
>>
>> stream_time =  (B.time_stamp - NS.start) / NS.abs_applied_rate + NS.accum
>>
>> Anyone can explain to me why the running_time use abs_rate but
>> stream_time use abs_applied_rate?
>>
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