Hello,

Sorry for my stupidity and lack of knowledge.

I'm searching a lossless codec for capturing purpose, I realize the WAV causing too many disk write but I've no idea which lossless codec is "fast and have average compression".

IMO, almost all loseless codec is racing for compression and functionality, but come to speed and resource-saving most of them still have the room to improve.

Appreciate for any suggestion, thanks in advance.


Rgds,
Johnson.

I'm not sure its possible to do what you want. Most lossless encoders are more than fast enough to do what you ask, but afaik all of them require wav input from another file.

I'm thinking ... can the codec accept input in the way of ACM or DirectShow?

Since I use Media Player Classic to capture Video and Audio in different file, if the codec cause too much CPU time, there may be frame skipping, using WAV is OK but when the background have any activity, serious frame skipping will occur, I hope a "fast and low resource" audio codec can help.

humm... I've googled a lil bit around the world, but I couldn't find a lossless ACM audio codec.... Maybe a modified version of TMPGenc support external codecs... then you could first record to PCM and then convert the audio stream to an other codec (like WavPack), but I really don't know if such a conveter exists, anybody knows?

That would be very nice if a ACM version of a famous lossless format could be built (FLAC/WavPack/OptimFrog/APE etc....)

otherwise, maybe ogg vorbis acm could be an alternative way.....? it isn't lossless.... but... could be a way...

Perhaps Oddcast's archiving feature would work for this, with its Live Recording and OggFLAC support.

Seems ACM is very tricky, few people work at it ... but I need it since VirtualDub need ACM to work.

OGG FLAC's support was disappointing, plain FLAC seems lot better.

You can't beat the physical reality of the universe. The incoming signal must be captured in real time, no matter which format you use to store it on disk. Serious audio recording is done only with very little, or nothing, else allowed to be active. Then there is no competition for resources and (if the system is functioning properly) no "frame skipping."

More powerful computers, with more RAM and disk, have a better chance of success at both recording and doing something else at the same time, but there are limits to every machine. Simply recording without processing (e.g. as straight PCM wav files in Windows) is the way to minimize the possibility of failure. If you want to store the recording in some compressed format (lossy or lossless), encoding it after it is securely captured on disk can always be done without fear of dropping bits due to resource competition. In this situation, multi-tasking does not result in something in one job being forgotten while another job has stage center.

I've been trying to do the exact same thing, losslessly compress the audio like i can with huffyuv for video for capturing in Virtualdub, but was unable to find such a codec.

On the other hand, the video stream is so large, the amount of space saved by compressing the audio is negligible.

no way WAV recording can be "too hdd intensive" 176kBps for CD quality is really nothing even few simultaneous recordings

That means the I/O is still the bottleneck, a lot of RAM or faster HD is the only way ...

Thanks for your answer.

I don't know what you mean about the I/O being a bottleneck. The audio input stream is real time, it does not pause just because you want to do something else for awhile, but the data rate for a few tracks is not all that great. More RAM and/or faster drives might make a difference in some instances, but the real problem is that some other activities can just take over so intensively that little else can be processed for that time. People do very successful multi-track (at least four or six tracks, maybe more) recording on older laptops with a 5400 RPM drive. They are just not foolish enough to try instant messaging and automatic internet updates at the same time.

I built the computer I record on when Win95 was in its prime. It is a 333MHz K6, with 64 meg RAM, and has a hard drive that is small and slow by today's standards. I only record two tracks at a time, but it does those in 24/96 without the slightest problem.

This may be helpful:

http://www.hydrogenaudio.org/forums/index....showtopic=47812

Thanks for your info.

It's good idea if it takes less than 5% CPU time, but VirtualDub seems not support DirectShow filter ...