deusven
4th January 2005, 15:51
Hi,
I'm fairly new to all this so forgive my newbieness...
When I demux and play back the AC3 track off a dvd, the ac3filter in windows allows you to select DRC or not and when you do use DRC you can see the little slider move up and down depending on the coming scene loudness etc. You can also choose the strength of the DRC and it all seems to work fine.
If I understood well, there is something called 'metadata' on the original AC3 track that allows such a decoder to 'know' what type of volume is coming up in the next scene and hence that little slider moves on its own to apply variable loudness.
Now what I don't understand is that when I simply change the bitrate of that same soundtrack with besweet (from 448 Kbps to 384 Kbps for example to reduce the size of the file) that same DRC system doesnt seem to work anymore...
Unless I don't understand something, the advantage of what I ve just described is that I can have the original AC3 track and apply custom levels of DRC without altering the source audio... the DRC is done when decoding rather than coming from the source (even if DVDs do have some DRC to start with).
Basically, if size wasnt a problem, i would just use the original AC3 track, but is it possible to lower the bitrate and keep those metadata things or whatever makes the decoding DRC possible?
thx for reading.
Sven.
I'm fairly new to all this so forgive my newbieness...
When I demux and play back the AC3 track off a dvd, the ac3filter in windows allows you to select DRC or not and when you do use DRC you can see the little slider move up and down depending on the coming scene loudness etc. You can also choose the strength of the DRC and it all seems to work fine.
If I understood well, there is something called 'metadata' on the original AC3 track that allows such a decoder to 'know' what type of volume is coming up in the next scene and hence that little slider moves on its own to apply variable loudness.
Now what I don't understand is that when I simply change the bitrate of that same soundtrack with besweet (from 448 Kbps to 384 Kbps for example to reduce the size of the file) that same DRC system doesnt seem to work anymore...
Unless I don't understand something, the advantage of what I ve just described is that I can have the original AC3 track and apply custom levels of DRC without altering the source audio... the DRC is done when decoding rather than coming from the source (even if DVDs do have some DRC to start with).
Basically, if size wasnt a problem, i would just use the original AC3 track, but is it possible to lower the bitrate and keep those metadata things or whatever makes the decoding DRC possible?
thx for reading.
Sven.