From ondrej.trubac at st.com Wed Jul 19 01:26:22 2006 From: ondrej.trubac at st.com (Ondrej TRUBAC) Date: Wed, 19 Jul 2006 10:26:22 +0200 Subject: [ID3 Dev] RE: Syncsafe words Message-ID: <00a401c6ab0d$04c6a690$7b048b0a@prg.st.com> I have looked into previous discussions and finally I am close to opinion that : "Prior to 2.4 the frame size was a 32 bit integer. In 2.4 it is a 28 bit syncsafe integer. However, if you generate a large frame in iTunes and save the tag as 2.4 you will see that the frame size is not syncsafe." Even because definition of frame size in 2.3 may seem vague little bit, I will take it as it is, thus no synchsafe size. Implementation could become more complicated in the case that whole tag in unsynchronised, e.g when frame size is 255 and flags are %11100000 xxx00000. But this situation can can occur rarely so I will ignore it and unsynchronisation will be not applied on frame headers as this is not critical issue in my application. Ondrej Trubac > > Hello, > > can somebody tell me if frame size for version 2.2 and 2.3 is > syncsafe word or not ? It seems that definition is not > complete here. Only in 2.4 documently it is stated clearly. > Thank you for help. > > > Ondrej Trubac > --------------------------------------------------------------------- To unsubscribe, e-mail: id3v2-unsubscribe at id3.org For additional commands, e-mail: id3v2-help at id3.org From wheeler at kde.org Mon Jul 31 16:23:55 2006 From: wheeler at kde.org (Scott Wheeler) Date: Tue, 1 Aug 2006 01:23:55 +0200 Subject: [ID3 Dev] Accessibility extension - second draft In-Reply-To: <6.2.0.14.2.20060704113743.0266fd68@pop3> References: <6.2.0.14.2.20060704113743.0266fd68@pop3> Message-ID: <200608010123.55370.wheeler@kde.org> On Tuesday 04 July 2006 13:27, Chris Newell wrote: > Dear all, > > Attached is second draft of the ID3v2 Accessibility addendum. I've > considered the comments received and made the following changes: > > 1) ?Audio-text frames now include an "equivalent text" string, rather than > an equivalent frame ID. > > 2) ?The MIME type of the audio clip is defined independently. > > 3) ?The ID3v2 unsynchronisation scheme is now mandatory when MPEG audio > formats are used. > > 4) ?An alternative scrambling scheme is defined for audio formats where the > ID3v2 unsynchronisation scheme is unsuitable. > > I'd be very interested to hear any comments. Hi Chris -- Sorry that after all my complaining on the earlier drafts that I never got back to you on this one. I was in the process of a move and didn't have broadband at home for a bit. [insert grumbling about Deutsche-Telekom here] The new draft looks good. The scrambling algorithm is a little exotic, but doesn't elicit any objections from my side. A few minor notes: - The link to the ID3v2.4 structure doc is incorrect. - The field ordering is a little strange. I'd expect text-encoding, text, mime-type, flags, data. (Two logical groups, one for text, the other for audio content.) Alternatively putting the flags at the front would fit with how some other ID3v2 elements are formatted, but the current layout wouldn't make my top 2-3 most obvious combinations. ;-) - You might consider a note on "pruning" -- i.e. under what circumstances ID3v2 implementations should discard (potentially using the frame header?) ATXT frames. Cheers, -Scott -- It may be true that you can't fool all the people all the time, but you can fool enough of them to rule a large country. --Will Durant --------------------------------------------------------------------- To unsubscribe, e-mail: id3v2-unsubscribe at id3.org For additional commands, e-mail: id3v2-help at id3.org From tmohr at s.netic.de Sun Jul 23 07:11:27 2006 From: tmohr at s.netic.de (Torsten Mohr) Date: Sun, 23 Jul 2006 16:11:27 +0200 Subject: [ID3 Dev] information about Frame decoding Message-ID: <200607231611.27261.tmohr@s.netic.de> Hi, i'm sorry if this is off-topic here, but maybe questions like mine are also handled here or somebody can give me help where to search for this. I'd like to decode an MP3 file. I can browse the file for the synch fields and the data related to it. I'd like to decode the frames i've found now to reconstruct the raw PCM data. There's quite some information about the structure of MP3 files available, but not that much about the audio data in the frames. What i've understood so far is: - the data in the frame may be CRC protected or not - i need to Huffman-Decode the frames data - what i get then depends on the type of frame, if it is mono, joint-stereo or stereo. - the decoded frames represent frequencies and their intensity. I now have some questions and it would be great if somebody could give me a hints here: - Is my understanding described above correct? - What ID3 tags do i need to decode the MP3 file? - Where can i get more information in detail about the next steps to do (Huffman-decoding and interpretation of the found data)? It would be great if anybody could give me a hint here. Thanks, Torsten. --------------------------------------------------------------------- To unsubscribe, e-mail: id3v2-unsubscribe at id3.org For additional commands, e-mail: id3v2-help at id3.org From bcorey at beatnik.com Mon Jul 24 11:13:03 2006 From: bcorey at beatnik.com (Brandon Corey) Date: Mon, 24 Jul 2006 11:13:03 -0700 Subject: [ID3 Dev] information about Frame decoding In-Reply-To: <200607231611.27261.tmohr@s.netic.de> References: <200607231611.27261.tmohr@s.netic.de> Message-ID: <20060724181303.GB8277@audioslave.beatnik.com> You don't need any ID3 info to decode the MPEG data.. they're totally separate. That said, your request is off topic here, but I'd recommend getting ahold of the ISO MPEG audio spec (ISO 11172-3). Brandon On Sun, Jul 23, 2006 at 04:11:27PM +0200, Torsten Mohr wrote: > Hi, > > i'm sorry if this is off-topic here, but maybe questions like mine > are also handled here or somebody can give me help where to search > for this. > > > I'd like to decode an MP3 file. I can browse the file for the > synch fields and the data related to it. > > I'd like to decode the frames i've found now to reconstruct the > raw PCM data. > > There's quite some information about the structure of MP3 files > available, but not that much about the audio data in the frames. > > > What i've understood so far is: > - the data in the frame may be CRC protected or not > - i need to Huffman-Decode the frames data > - what i get then depends on the type of frame, if it is > mono, joint-stereo or stereo. > - the decoded frames represent frequencies and their intensity. > > > I now have some questions and it would be great if somebody could > give me a hints here: > > - Is my understanding described above correct? > > - What ID3 tags do i need to decode the MP3 file? > > - Where can i get more information in detail about the next steps > to do (Huffman-decoding and interpretation of the found data)? > > > It would be great if anybody could give me a hint here. > > > Thanks, > Torsten. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: id3v2-unsubscribe at id3.org > For additional commands, e-mail: id3v2-help at id3.org > --------------------------------------------------------------------- To unsubscribe, e-mail: id3v2-unsubscribe at id3.org For additional commands, e-mail: id3v2-help at id3.org From chris.newell at rd.bbc.co.uk Tue Jul 4 04:27:10 2006 From: chris.newell at rd.bbc.co.uk (Chris Newell) Date: Tue, 04 Jul 2006 12:27:10 +0100 Subject: [ID3 Dev] Accessibility extension - second draft Message-ID: <6.2.0.14.2.20060704113743.0266fd68@pop3> Dear all, Attached is second draft of the ID3v2 Accessibility addendum. I've considered the comments received and made the following changes: 1) Audio-text frames now include an "equivalent text" string, rather than an equivalent frame ID. 2) The MIME type of the audio clip is defined independently. 3) The ID3v2 unsynchronisation scheme is now mandatory when MPEG audio formats are used. 4) An alternative scrambling scheme is defined for audio formats where the ID3v2 unsynchronisation scheme is unsuitable. I'd be very interested to hear any comments. Best regards, Chris -------------- next part -------------- An HTML attachment was scrubbed... URL: -------------- next part -------------- ____________________________________________ Chris Newell Lead Technologist Technology Group BBC New Media & Technology Kingswood Warren, Woodland Way, Tadworth Surrey KT20 6NP UK Tel: +44 (0)1737 839659 Fax: +44 (0)1737 839665 mailto:chris.newell at rd.bbc.co.uk -------------- next part -------------- An HTML attachment was scrubbed... URL: -------------- next part -------------- --------------------------------------------------------------------- To unsubscribe, e-mail: id3v2-unsubscribe at id3.org For additional commands, e-mail: id3v2-help at id3.org From ondrej.trubac at st.com Tue Jul 18 08:32:08 2006 From: ondrej.trubac at st.com (Ondrej TRUBAC) Date: Tue, 18 Jul 2006 17:32:08 +0200 Subject: [ID3 Dev] Syncsafe words Message-ID: <003601c6aa7f$54ce69e0$7b048b0a@prg.st.com> Hello, can somebody tell me if frame size for version 2.2 and 2.3 is syncsafe word or not ? It seems that definition is not complete here. Only in 2.4 documently it is stated clearly. Thank you for help. Ondrej Trubac --------------------------------------------------------------------- To unsubscribe, e-mail: id3v2-unsubscribe at id3.org For additional commands, e-mail: id3v2-help at id3.org