Encoding Dolby Pro-Logic

[simple_simon]

I have a pal dvd audio track that I want to slow down to ntsc speed and reencode to aac. The track is 2-channel stereo encoded with dolby pro-logic surround information. Is there any way to reencode this this track and maintain the pro-logic information. I've only been able to find information on how to downmix 5.1 audio to 2-channel dolby pro-logic but not how to reencode 2-channel dolby pro-logic. I usually use eac3to to slowdown the track to the proper speed but I also know how to do it with audacity if anybody knows how to do this with either of those programs or knows of some other program that can do it.

[SeeMoreDigital]

I'm interested in this too...

Some time ago I asked if it was possible to re-encode a 2Ch "pro-logic" source to something approaching 5.1Ch ;)

[tebasuna51]

The dpl info is preserved when resample and recode (more or less).
With eac3to and NeroAacEnc at same folder you can try:

eac3to input.ac3 output.m4a -slowdown

But the aac stream don't have a flag, like ac3, to enforce the use of DPL decoder in receivers, you need force the decoder manually.

To upmix a 2.0 dpl ac3 to 5.1 you can use Foobar2000 and the foo_dsp_fsurround plugin.

[simple_simon]

I don't currently have a amplifier with pro-logic support. Is there any way to test the re-encoded file with software to determine if the pro-logic information is there or not?

[tebasuna51]

Like I say before you can try upmix the 2.0 to 5.1 (Foobar2000 + foo_dsp_fsurround plugin) and see if there are a clear channel separation.