AC3 Metadata

[nimrodim]

I am looking for away to inspect the metadata of AC3 files.

Suggestion would be appreciated.

[tebasuna51]

http://www.atsc.org/cms/standards/a_52b.pdf

[nimrodim]

Anyone know of a utility\program I could use to see this information?
I am mostly interested in finding out the setting for dialogue normalization in a given ac3 file - especially when i want to re-encode it at a different bit rate.

I use wavtoac3encoder for my AC3 encoding and i was wondering if any of the following actually have an effect on the actual encoding of the AC3 beyond the Meta-data:
Changing Bit-stream info meta-data such as center and surround mix level and Dolby surround mode.
Dynamic range compression and dialogue normalization.

[Hagbard23]

when you use EAC3TO for AC3 to WAV conversion, then EAC3TO will return the Dialog Normalization it has detected in the AC3 Stream.(You see it in the progress-window) - it is the best option to use YRaen's GUI for EAC3TO, but DO NOT use the newest Version. Use the older one instead - because the new one is extremely confusing. You'll find them both on the download site.

http://forum.doom9.org/showthread.php?t=125966(EAC3TO)
http://www.mediafire.com/?sharekey=483e9d29164ef2f3d5a101cf914073b417c134476594f301(Yraens GUI)
http://www.videohelp.com/download/AftenGUI-1.4.zip (direct download AFTEN GUI)
http://code.google.com/p/wavtoac3encoder/downloads/list (newest AFTEN GIT's)

well, thats the way i do it, because for AFTEN, one has to recode the AC3 into WAV anyway.

P.S. Because EAC3TO does the conversion into one WAV File only (not channel-splitted as WAV2AC3 expects it) it would be an option to use AFTENGUI(which accepts multichannel WAV) for the AC3-Work and pump it up with the newest AFTEN GIT's you get from the Download-Page of WAV2AC3 Encoder. Don't forget to check the Option "Read to End Of File" in AFTEN GUI, because otherwise WAV reading is limited to 1GB.

Sorry - but i do not know any tool, which reads the AC3 metadata directly

€dit: Yes Tebasuna, as an Audio-Pro you have to point your intelligence out - i know that i do not know everything - i never said i do.

You can input multichannel wav without problem.
How?

[tebasuna51]

MediaInfo can show dialnorm and other metadata. Also eac3to can show dialnorm.

Metadata (like mix-levels, Surround-mode, DRC and DialNorm) don't affect the encoder process, only add the values to frame header, audio data bitstream is the same.
These metadata can affect the decoder process, but the decoder can be instructed to ignore them.

I don't recommend you use Aften (wavtoac3encoder) with DRC distinct of None. The current implementation of DRC in Aften isn't finished with outputs very different than certified encoders.

[tebasuna51]

...
P.S. Because EAC3TO does the conversion into one WAV File only
You can use eac3to to output multiple monowav files

(not channel-splitted as WAV2AC3 expects it)
You can input multichannel wav without problem.

Don't forget to check the Option "Read to End Of File" in AFTEN GUI, because otherwise WAV reading is limited to 1GB.
The limit is 4GB.

but i do not know any tool, which reads the AC3 metadata directly
Try this tool LeeAudBi03b (http://www.sendspace.com/file/dfdv3v), works with AC3 at least.

[kieranrk]

You can put some printfs in the ffmpeg ac3 decoder to view the metadata.

[nimrodim]

Try this tool LeeAudBi03b (http://www.sendspace.com/file/dfdv3v), works with AC3 at least.


Thank you...that was exactly what I was looking for.

And thanks for clarifying the questions I had regarding AC3 meta-data not affecting the encoded ac3.

[Hagbard23]

Yeah - cool tool indeed, i like it.

Everywhere something new to learn - thanks tebasuna for the authoring of this program and for linking it up for us.

[tebasuna51]

...
You can input multichannel wav without problem.

How?
Sorry, I don't see your question.

In Wav to AC3 Encoder menu 'File' -> 'Add files' (or rightclick over 'FilePath' area) you can add a single multichannel wav.

This is the natural way to send input file to Aften encoder.

[Hagbard23]

The last time i tried it, results in the problem, that WAV2AC3 recognizes this added wav-file as a mono wave - and i was only able to link it to one single channel. Instead, AFTENGUI processes it without problems....

But: I'm gonna check it again, when i come home and edit this post here with my results. ATM I am (as the most people in CET) at work. But thanks for considering an answer to my question....

€dit: Neither Yr's EAC3TO GUI nor EAC3ToGUI are able to output 6x mono WAV Channels - at least i don't see any option for that - maybe i am blind. But you are right in the point of multichannel input to WAV2AC3.

The MUX-WIZARD is somewhat confusing, because it maps the stereo WAV only to the left channel. But in the end AFTEN do not use this MUX-WIZARD until you check "multiple mono input".

Thats the reason, for my confusion...

But thanks for rectifying the facts for me and others...

[tebasuna51]

€dit: Neither Yr's EAC3TO GUI nor EAC3ToGUI are able to output 6x mono WAV Channels - at least i don't see any option for that
The command line is:

eac3to source mono.wavs

With EAC3ToGUI put like destination file mono.wavs
Yr'sGUI is not for me.
You can use also UsEac3to.