Re: How to play audio and video from two different sources

Hi Alessandro (sorry I have switched "nome e cognome"... I'm the italian guy
you helped a month ago in my post "Help regarding writing a Source Filter").

Thanks for the info, I saw the statement with IMediaSample::SetTime(). Now I
have the info for proceeding writing the second pin for the audio.

Ciao

Dev


"Alessandro Angeli [MVP::DS/MF]" <nobody@xxxxxxxxxxxxxxxxxx> wrote in
message news:#4m9jubTGHA.4600@xxxxxxxxxxxxxxxxxxxxxxx
DevX wrote:

Hi Angelo,

I don't know who Angelo is, but hi to you to :-)

How I set the timestamp on the samples? My samples are
only a bunch of bytes representing a YUV buffer or a WAV
sample, there is some form of DirectShow pre-processing I
must do? Currently the only timing facilities I have on
my filter are the same found on the BouncingBall, in the
Notify() function were I set the repeat time of the
frame.

If you copied CBallStream::FillBuffer(), then you are
calling IMediaSample::SetTime() to set the sample's
timestamp. The stop time is not really needed, but the start
time is important: as long as you set the correct start time
to each audio and video sample, the renderers will keep the
streams in sync.

How to calculate the start times depends on how you produce
the data, but usually the start time starts at 0
(CBallStream::OnThreadCreate()) and for each sample S,
start_time[S] = start_time[S-1] + duration[S].

With video, duration[S] is usually a known value
(VIDEOINFOHEADER::AvgTimePerFrame), if the frame rate is
constant.

With PCM audio, duration_in_secs = 8 * buffer_size /
wBitsPerSample / nChannels / nSamplesPerSec or
duration_in_secs = buffer_size / nAvgBytesPerSec (since, for
PCM audio, nAvgBytesPerSec = wBitsPerSample * nChannels *
nSamplesPerSec / 8).

Thanks a lot for the help and the patience.

You're welcome.


--
// Alessandro Angeli
// MVP :: DirectShow / MediaFoundation
// a dot angeli at psynet dot net




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