(to take advantage of the latest windows media 9)
Thanks in advance
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| Unofficial VirtualDub Support Forums > Codec Discussion > Is Their A Wma Acm Engin |
| Posted by: Cerberus Jan 27 2003, 11:14 AM |
| Hi I was just wanting to know if their an WMA acm engin that i could use for audio on avi files. I know you can encode a WMA file and change the header to a wav file then tie it into the video. I didnt find anything much by seching google for "ACM WMA" so if anyone knows of this or knows its a bad idear please let me know. (to take advantage of the latest windows media 9) Thanks in advance |
| Posted by: jcsston Jan 27 2003, 05:21 PM |
| I think WMA in avi files isn't a great idea. Because of the lack of legal ACM WMA encoders and decoders. |
| Posted by: ChristianHJW Jan 27 2003, 09:34 PM |
| M$ has promised a VfW WMV 9 codec recently on Doom9 .. but no mention of a WMA ACM codec ... |
| Posted by: Neo Neko Jan 27 2003, 11:14 PM |
I will have to read again but I believe Amir mentioned WMA ACM as well. But ATM both are vapor ware so no sense holding your breath for now. And even once they are out their portability is limited.  |
| Posted by: phaeron Jan 28 2003, 07:58 AM |
| Windows Media Audio V1 and V2 both have ACM engines -- that is, in fact, the original form of the codecs as they were used in the Netshow Encoder, before it became Windows Media Encoder. However, the codecs aren't usable in AVI files, because specific unlocking codes must be supplied to the codecs for them to respond, presumably as a licensing mechanism. The incarnations of the "DivX Audio" codec are simply versions of the WMA ACM drivers that have had their authentication checks (badly) disabled; the ID tags (0x0160/0x0161) were never changed, so DivX Audio picks up WMA streams that the real WMA codec refuses to decode. Audio Compression Manager (ACM) was designed to work with audio formats that have constant block sizes (nBlockAlign), so even if the newest WMAs are ported back to ACM, I wouldn't expect VBR or lossless modes of operation. |
| Posted by: ChristianHJW Jan 28 2003, 04:00 PM | ||
I was just going to add this, but you beat me to it Avery. Maybe one day someone will be able to make a UCI wrapper for WMA and WMV9  .... |
| Posted by: Cerberus Jan 28 2003, 05:10 PM |
 thanks for youre input much apreciated....  |
| Posted by: outlyer Jan 28 2003, 07:04 PM | ||
When I red Amir's post I just wondered, now that M$ is giving a second chance to AVI, if they don't plan to extend the AVI specification to support VBR audio. What do you think? Could this be done? Although it could break backwards compatibility but they don't usually care much for old systems... (whispering) Christian, I think they fear matroska  |
| Posted by: fccHandler Jan 28 2003, 07:10 PM |
| (whispering) Just as a curiosity, I remember that msaud32.acm can be unlocked for general use by changing one byte in the file! |
| Posted by: Neo Neko Jan 28 2003, 08:22 PM | ||
It may have been designed that way. And that may be how it is supposed to be used. But I know of a few ACM codecs who via one method or another do VBR or ABR. The lame ACM being one of em. Not that it works well.  |