RIFF and RF64 codec ID.

[Dave1024]

Hello,

I had a RIFF wave file. Media Info describes as given below

Audio

ID/String : 2 Format : PCM Format_Settings_Endianness : Big Format_Settings_Sign : Unsigned CodecID : in24 Duration/String : 26s 0ms BitRate_Mode/String : Constant BitRate/String : 2 304 Kbps Channel(s)/String : 2 channels SamplingRate/String : 48.0 KHz BitDepth/String : 24 bits StreamSize/String : 7.14 MiB (7%) Language/String : English Encoded_Date : UTC 2009-04-01 16:01:10 Tagged_Date : UTC 2009-04-01 16:01:10

Here in this case Codec ID is 'in24'. Some times for some sample files it shows 1.
My doubt is which byte/bit in the 44 byte wave header describe this ?(Is my assumption wave header is 44 byte long is correct?)

Is this specific filed available in RF64 (Wave file of size > 4 GB) if yes which byte/bit will hold this value?

Thanks
Dave

[El Heggunte]

For starters: https://ccrma.stanford.edu/courses/422/projects/WaveFormat/

And no, a WAV header is not limited to 44-bytes, especially when it stores constant-bitrate compressed audio

As for RF64, I know nothing about it, sorry

[Cornucopia]

IIRC, RF64 is totally backward-compatible with RIFF WAV/BWF...(yep, see here: http://www.google.com/url?sa=t&rct=j&q=rf64%20file%20format&source=web&cd=2&cad=rja&ve...48340889,d.aWc)

As El Heggunte mentioned, WAV headers vary considerably, based on what info is needed to be conveyed. They are portioned into "Chunks" just like AVI is (neither of which have such strict byte length limitations).

Scott

[El Heggunte]

@ Scott: many thanks for the PDF

@ Dave: two more pages,

http://www.sonicspot.com/guide/wavefiles.html

and

http://www.piclist.com/techref/io/serial/midi/wave.html ( this one is very funny indeed )

[Dave1024]

Scott & El Heggunte

Thanks to the prompt replays.

But what is the base for Media info display codec ID - I mean which bit group contribute this value ? Also i am sure there is no Codec ID field in the wave header.

Any inputs on the same ?

Thanks
Dave

[Cornucopia]

Straight from the horse's mouth: http://mediainfo.sourceforge.net/en/Support/Tags. Half-way down, in Tech. Info. Codec ID = "format". IOW, it takes what's available from the RIFF's format chunk and maps/translates it to what would be similar in other containers' CODEC ID field. Of course, you could always peek at the source code, too.

What I've been saying for a while: it would be so much better if MediaInfo ALSO explained (as a tooltip or something) how it arrived at a particular field's value & where it got the info from. I believe much of what people consider to be INACCURATE from MediaInfo has to do with this disparity or fuzziness.

Scott

BTW, El Heggunte, you're welcome. There are many helpful (and freely available) docs over at the EBU.

[jagabo]

But what is the base for Media info display codec ID - I mean which bit group contribute this value ? Also i am sure there is no Codec ID field in the wave header.

It's the format field in the header. AudioFormat in the Stanford.edu document linked to by El Hegunte. Compression Code in the sonicspot page, wFormatTag in the piclist doc. It's simply a number from 1 - 65,535 indicating what codec is used. I don't know how MediaInfo translates that number into a fourcc-like code.

[El Heggunte]

I don't know how MediaInfo translates that number into a fourcc-like code.

Me neither, especially because, and AFAIK, there is NO twocc dedicated to the "bit-depth" and/or "endianness" of uncompressed audio

Yet another link

http://wiki.multimedia.cx/index.php?title=Twocc

[jagabo]

Here are the definitions from Microsoft's SDK header files:
http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Docs/MMREG.H

See the WAVE_FORMAT_x definitions.

[El Heggunte]

Looks like I have found it, at last

http://wiki.multimedia.cx/index.php?title=QuickTime_container#Audio_FOURCCs

[jagabo]

LOL, I just found that too! It's Quicktime that defines those audio fourcc codes.

Presumably, MediaInfo derives that fourcc by seeing the audio is PCM, 24 bit, integer, big endian.