Multichannel audio with WM ASF Writer
Jorge Muria
I want to encode a WM File with multiple audio (4 channels). I saw
that the filter in GraphEdit shows 2 input pins called (audio 01 and
video 01). I suppone that It means that it can be instanciated the
audio 02 pin. I've been looking for it in the WM Format SDK help and
the Windows Media Encoder SDK. The only reference about encoding
multichannel is though the IWMEncAudioSource interface but I cannot
instance it from the "WM ASF Writer" filter.
Is there any way to encoder multiple audio channels usign the "WM ASF
Writer" filter?. I'm trying it using two stereo wav files as audio
source.
Thank you.
Iain
I haven't tried it, but I wouldn't be entirely sure that the Asf Writer can
do this.
To start with you need to make sure you have applied a profile which
supports more than one audio channel (and the 2 streams are not bound
together in a MBR group).
If you are lucky you will then see an ASF Writer filter with two audio
input pins.
If you don't try the same with the Encoder.
If that fails, you will have to write something with the Format SDK.
Iain
Chris P. [MVP]
And I guess the other question is do you want a 4-channel, single audio
stream or two 2-channel streams or four 1-channel streams?
If you want it as a single stream the audio format needs to be
WAVEFORMATEXTENSIBLE from the upstream filter. For a test you can use a
wave file recorded in this format.
John
replayed independently as well as in sync together) from a multichannel sound
capture card using a WMA Pro 5.1 codec? If so, how does one effect channel
selection upon playback in windows media player?
John
Chris P. [MVP]
> Can one encode a live 4 channels (4 microphones that must be able to be
> replayed independently as well as in sync together) from a multichannel sound
> capture card using a WMA Pro 5.1 codec? If so, how does one effect channel
> selection upon playback in windows media player?
Encoding is not a problem. Playback probably will be a problem as without
a 3rd party plug-in for Media Player there is no channel selection or mix
control available. I believe you would have to write your own plug-in to
get what you want.
John
simultaneously from an 8-channel soundcard (M-Audio's Delta 1010), but I only
can get 2 channels (a single stereo pair) at any one time. Is this purely a
manufacturer's driver issue or should it be possible with any multichannel
sound capture card that supports WDM? In that regard, the Delta 1010 is
supposedly very compatible with WDM and DirectSound. To make my inquiry more
concise, do you know of any specific sound card and configuration that can
support live encoding of more than a single stereo pair into a 5.1 or 7.1 wma?
Thanks again,
John
Chris P. [MVP]
> Thank you for your response. I have tried to encode more than 2 channels
> simultaneously from an 8-channel soundcard (M-Audio's Delta 1010), but I only
> can get 2 channels (a single stereo pair) at any one time. Is this purely a
> manufacturer's driver issue or should it be possible with any multichannel
> sound capture card that supports WDM? In that regard, the Delta 1010 is
> supposedly very compatible with WDM and DirectSound. To make my inquiry more
> concise, do you know of any specific sound card and configuration that can
> support live encoding of more than a single stereo pair into a 5.1 or 7.1 wma?
You need to use a sound card that exposes the input channels as a single
device, not as multiple stereo pairs. I'm not overly familiar with the
Delta 1010 to know what method it uses. The catch is the stream format
must be WAVEFORMATEXTENSIBLE with the desired number of channels.
For testing purposes it easiest to start with Windows Media Encoder, if it
works there then it should work with the ASF writer provided the format is
correct.