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View Full Version : ISDB-T International (Brazil) and it's weird audio codec


Rain_1
21st March 2012, 02:31
Hi there peeps.

This seemed like the best place to create this thread. If there's a better place for it, lemme know.

I've recently started trying to record Over-The-Air HDTV signals down here in Brazil and i'm having some issues.

We use a modified version of the Japanese ISDB specs on our Terrestrial broadcast, and my Tuner spits out a weirdly formatted .MPG as the recording.

The video, however, is not really a problem. Dgavcdec109 (discontinnued, I know) properly identifies all the streams and Demuxes them without any problems. My problem is working with the audio tracks that come out of that demuxing.

Here are the audio formats the Standard supports:

Multi Channel 5.1: MPEG-4 AAC@L4 (Advanced Audio Coding, Level 4) or MPEG-4 HE-AAC v1@L4 (High Efficiency AAC, Version 1, Level 4)
Stereo: MPEG-4 AAC@L2 (AAC Level 2) or MPEG-4 HE-AAC v1@L2 (HE-AAC, Version 1, Level 2)

And I can't, for the life of me, find HE-AAC compatible Avisynth plugins or Windows Software to convert it to something I can work with (like AC3 or ANYTHING ELSE). I've been looking around for a while and NOTHING seems to identify the audio stream.

I know that just talking about it without providing any samples is not really useful, so I prepared two samples for you guys, mostly because I wanted somebody else to verify that those are HE-AAC Streams and that I'm not going crazy. Maybe there's something messed up on the Headers that I'm not noticing? I have little experience in looking at audio files on HexEditors and detecting headers, so bear with me.

One is a 1 minute sample, around 100 megs, with 2 audio Streams (I BELIEVE one of them is silent, but I'm not sure).
The other one is a couple of seconds sample, around 5 megs, with only one audio Stream.

I'm providing both the untouched .MPGs the decoder spits out and the untouched .AACs that dgavcdec109 spits out.

Sample 1 (http://rain01.free.fr/ISDBT/test_1min.mpg) - Sample 1 Audio 1 (http://rain01.free.fr/ISDBT/test_1min%20PID%20113%20DELAY%2012067ms.aac) - Sample 1 Audio 2 (http://rain01.free.fr/ISDBT/test_1min%20PID%20112%20DELAY%20-165ms.aac)

Sample 2 (http://rain01.free.fr/ISDBT/test_seconds%20PID%20113%20DELAY%20864ms.aac) - Sample 2 Audio (http://rain01.free.fr/ISDBT/test_seconds.mpg)

If anybody can help me try to piece this one together, i'll be forever grateful. :D

Edit: If more samples are needed, I'll gladly provide them. Just ask away.

Rain_1
21st March 2012, 03:53
After reading the FAQs and going deeper into some other threads, it seems that all my questions are already answered! I'm very sorry. I should've done more research.

I'll get back to this thread and put down some important information and sources for future lazy persons like me.

Blue_MiSfit
21st March 2012, 08:24
No worries, there's no harm in asking for help. I'm glad you found what you were looking for!

SeeMoreDigital
21st March 2012, 19:12
After reading the FAQs and going deeper into some other threads, it seems that all my questions are already answered! I'm very sorry. I should've done more research.

I'll get back to this thread and put down some important information and sources for future lazy persons like me.
Indeed... I found your other topic about this issue here: http://forum.doom9.org/showthread.php?t=164485

Lyris
5th April 2012, 02:45
It's really not a weird codec at all. The same is used on terrestrial HDTV in the UK (DVB-T2).