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682 discussions

Xing ID3 and VBR
by Russell O'Connor 07 Nov '02

07 Nov '02

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 [To: mad-dev(a)lists.mars.org] Is it possible for someone to elighten me on the relationship between ID3 v2 tags, Xing headers, and figuring out the lenght of VBR files? Specifically, if I get my application to read ID3 tags, will I be able to find out the decoded length of an audio file without going through and counting all the frames? - -- Russell O'Connor <http://www.math.berkeley.edu/~roconnor/> ``[Law enforcement officials] suggested that the activists were stopped not because their names are on the list, but because their names resemble those of suspected criminals or terrorists.'' -- SFGate.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (SunOS) Comment: For info see http://www.gnupg.org iD8DBQE9yJCouZUa0PWVyWQRAhKWAJ9xTedVA5ESzXPZWXblV702ZqI2mACeKmp1 toxRK2xxxbp3Rhc7FAcI8J0= =/ljn -----END PGP SIGNATURE-----

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Frame reading
by Nelly.TOURNIER＠wavecom.fr 06 Nov '02

06 Nov '02

Hello all, My request concerns the mad_frame_decode function. I would like the frames to be read word by word (16 bit ) instead of byte, in the "bit reservoir"... Does anyone have idea? Thanks, Nelly

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Re: [mad-dev] Xing ID3 and VBR
by Joe Drew 06 Nov '02

06 Nov '02

Russell O'Connor wrote: > On Tue, 5 Nov 2002, Joe Drew wrote: >>if (is_constant_bit_rate(file)) > > Oh, Is this easy to figure out? Err, I should have specified - this is a semi-heuristic: decode the first n (I think for me n = 10) frames and see if the bitrate changes. If so this is a vbr file. Otherwise it's not. This heuristic is pretty accurate in my experience.

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Can ID3v2.4 tag be only in middle????????
by rahul_dsp 30 Oct '02

30 Oct '02

Hi All, I am trying to implement a audio decoder on DSP using assembly language. I want to decode ID3v1 & ID3v2.2 and parse ID3v2.3 and ID3v2.4. Regarding parsing out ID3v2.3 I am facing out one problem. Standards of ID3v2.4 says that I can be present in the middle of the file.What it means that some audio data can be there and then ID3 tag and then audio data. Information about this ID3v2.4 tag will be given by the SEEK frame in minimum offset from the end of the tag. The problem is that it is not clear or nowhere said that First ID3v2.4 will be present in beginning or audio data. Suppose that only IDv2.4 tag is present in a mp3 file and no other v1 or v2.2 or v2.3 are present. In case second ID3v2.4 tag is also present then SEEK frame in first tag will tell the location of the second tag. My question is is it possible that no tag is present in the very beginning and file is starting with mp3 audio data and then ID3v2.4 tag and then again audio data. Following is the representation of what I want to ask. 1. ____________________________________________________________________ |ID3v2.4 tag |Audio Data | ID3v2.4 tag | Audio Data | |____________|_________________|________________|____________________| 2. ____________________________________________________________________ |Audio Data |ID3v2.4 tag | Audio Data | ID3v2.4 tag | |____________|_________________|________________|____________________| First case is ok ...is it possible that second case can also exist. What I am assuming that second case is not possible. Please correct me if I am wrong.Or please direct me in right direction. Warm Regards, Rahul Mehta. --------------------------------------------- http://mail.indiainfo.com India's first ISO certified portal Check world time at http://time.indiainfo.com

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Can ID3v2.4 tag be only in middle????????
by rahul_dsp 30 Oct '02

30 Oct '02

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dct32 function for DSP
by Nelly.TOURNIER＠wavecom.fr 28 Oct '02

28 Oct '02

Hello All I am trying to optimize the dct32 function with loop and accumulations but it does not really work... Did anyone already worked on this toppic? Thanks, Nelly

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search_tags behavior in libid3tag
by Matt Reppert 20 Oct '02

20 Oct '02

Hi, I've been trying to get xmms-mad to stop crashing on various sometimes odd audio streams. Recently I was trying to get it to read a group of MP3 files I picked up somewhere some time ago and traced the cause of their crash to the fact that if a stream doesn't have ID3 tags, bad things happen. But libid3file was refusing to load tags for streams that I knew had them. Turns out that my files have nice, valid ID3v1 info at the beginning of the stream and something that libid3file rejects at the end. (I don't know why yet.) In this case, libid3file refuses to return *any* ID3 info, even the valid stuff that it loaded from the beginning. Why is this being done? I got it to return tag info with the following. This is in search_tags: --- mad-0.14.2b/libid3tag/file.c 2001-11-01 14:27:38.000000000 -0600 +++ mad-devel/libid3tag/file.c 2002-10-20 09:08:12.000000000 -0500 @@ -256,7 +256,8 @@ if (0) { fail: - result = -1; + if (file->ntags < 1) + result = -1; } clearerr(file->iofile); Matt

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about the compliance test result on libmad ( ver 0.14.2b) -1
by pltsai＠globalunichip.com 19 Oct '02

19 Oct '02

Hi, everyone Is there anybody with the experience to do the compliance test using ver 0.14.2b code ?! I use madplay to decode the compliance bitstream : he_mode.bit My output file is he_mode_intel_24.hex The output file generated by L3dec.exe is he_mode.hex. The compliance test result : 251137 samples are compared. and the maximum difference :0.489849 the root mean square is 0.0619873 You can find the 11701th sample: the he_mode_intel_24.hex is 123809 the he_mode.hex is f1e918 It has exceeded the maximum difference accoring to the compliance test. Also in 11702th .... The result can't meet the full compliance request. Also I doubt why the file size of output hex file is different with the hex file generated by l3dec.exe the following is libmad build environment My configuration is FPM_INTEL,_LIB,HAVE_CONFIG_H,ASO_ZERO_CHECK,WIN32, _MBCS_DEBUG The decode command : -d -b 24 -o he_mode_intel.hex he_mode.bit Can anyone give me the hints where I might go wrong?! PS : the file size of output hex file in FPM_ARM is also different with the output hex file in FPM_INTEL or the hex file gererated by l3dec.exe I will attach the two hex file in another mail. Best Regards, Sunny (Pei-Lin Tsai)

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Ref:Help! Frames not being rendered
by rahul_dsp 19 Oct '02

19 Oct '02

Hi Mark, I came to know that You have a file with ID3v2.2 tag I am looking for this specified tag. If you can share that tag with the list I would be very thankful to you. I have refered to the standards and specifications on ID3lib.org but to get more clearer picture I need the real tag. Actually I am trying to decode and parse these tags using Assembly Language. Also if You have ID3v2.4 tag share that too. Please share with me. Thanks & Regards, Rahul Mehta On Thu, 10 Oct 2002 06:28:07 -0700 mad-dev-request(a)lists.mars.org wrote: >Send mad-dev mailing list submissions to > mad-dev(a)lists.mars.org > >To subscribe or unsubscribe via the World Wide Web, visit > http://www.mars.org/bin/mailman/listinfo/mad-dev >or, via email, send a message with subject or body 'help' to > mad-dev-request(a)lists.mars.org > >You can reach the person managing the list at > mad-dev-admin(a)lists.mars.org > >When replying, please edit your Subject line so it is more specific >than "Re: Contents of mad-dev digest..." > > >Today's Topics: > > 1. Help! Frames not being rendered. (Mark Malson) > 2. Re: Help! Frames not being rendered. (Rob Leslie) > 3. Re: Mac OS9 / CodeWarrior (pmisteli) > 4. Re: Bug in libid3tag (Martin Hedenfalk) > >--__--__-- > >Message: 1 >Date: Wed, 09 Oct 2002 22:38:43 -0400 >From: Mark Malson <mark(a)mmalson.com> >To: Rob Leslie <rob(a)mars.org>, <mad-dev(a)lists.mars.org> >Subject: [mad-dev] Help! Frames not being rendered. > >I have a file that was tagged with an id3v2.2 tag. When I go to write >out >the tag, most of the frames are not being written out. > >When the tag is parsed, it hits this snippet in id3_frame_parse >several >times: > > if (ID3_TAG_VERSION_MAJOR(version) == 2) { > xid[0] = 'Y'; > xid[1] = id[0]; > xid[2] = id[1]; > xid[3] = id[2]; > > id = xid; > > flags |= > ID3_FRAME_FLAG_TAGALTERPRESERVATION | > ID3_FRAME_FLAG_FILEALTERPRESERVATION; > } > >...and the flag bits that are being set, as far as I can tell, >function >solely to prevent the frame from being rendered. > >I'm guessing that because these are older frame types (TT2, TP1, >etc.) that >they are being parsed and flagged so that the lib can create a frame >with a >newer tag type? and write it out instead? But it looks like most of >my >frames have these flags set. > >Sometimes the frames DO get written out and but I haven't figured out >under >what conditions yet. > >Is there a function lying around that prints the contents of the >frames as >they exist in memory? It would be helpful to me to see a before and >after >snapshot of my frames. > >Thanks, > >- Mark Malson > mark(a)mmalson.com > > --------------------------------------------- http://mail.indiainfo.com India's first ISO certified portal Check world time at http://time.indiainfo.com

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Help! Frames not being rendered.
by Mark Malson 16 Oct '02

16 Oct '02

I have a file that was tagged with an id3v2.2 tag. When I go to write out the tag, most of the frames are not being written out. When the tag is parsed, it hits this snippet in id3_frame_parse several times: if (ID3_TAG_VERSION_MAJOR(version) == 2) { xid[0] = 'Y'; xid[1] = id[0]; xid[2] = id[1]; xid[3] = id[2]; id = xid; flags |= ID3_FRAME_FLAG_TAGALTERPRESERVATION | ID3_FRAME_FLAG_FILEALTERPRESERVATION; } ...and the flag bits that are being set, as far as I can tell, function solely to prevent the frame from being rendered. I'm guessing that because these are older frame types (TT2, TP1, etc.) that they are being parsed and flagged so that the lib can create a frame with a newer tag type? and write it out instead? But it looks like most of my frames have these flags set. Sometimes the frames DO get written out and but I haven't figured out under what conditions yet. Is there a function lying around that prints the contents of the frames as they exist in memory? It would be helpful to me to see a before and after snapshot of my frames. Thanks, - Mark Malson mark(a)mmalson.com

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