| Author |
K700i - use AAC to fit an hour of music |
michka
Joined: May 17, 2004
Posts: > 500
From: Brussels-Belgium
PM |
Sorry max_wedge but you are wrong. wav files can contain any sort of compressed audio. That is the definition of a wav file. PCM is indeed linear digitized sound at regular time interval, the frequency of which is called the sample frequency. But this is only one sort of wav file. It is indeed used to store sound on CDs.
But, I say it once again, wav files can contain any type of compressed sound data. Just as avi files can contain uncompressed or compressed movies.
I know it, I am the developer of a sound conversion, editing and recording program intended for the PC-telephony industry.
Just download the Microsoft SDK and have a good read, pal.
Edit: Oh and one additional thing: it is not because a PCM file (let it be wav or any other format) is not created that you don't need to go through an uncompressed PCM intermediate to transcode from mp3 to mp4. In fact you absolutely need to, but chunks of the intermediate PCM data can very well remain stored in memory.
Edit 2: By the way, you want a very easy way to check that what I am saying is true? Under Windows, just open Sound Recorder, record a small piece of sound (silence will do it too), click on "File/Save as" and in the Save As dialog box, look at the various possibilities in the Format drop down menu.
_________________
Pedestrian: don't run, my car is faster anyway.
[ This Message was edited by: michka on 2005-03-20 14:24 ]
[ This Message was edited by: michka on 2005-03-20 14:31 ]
[ This Message was edited by: michka on 2005-03-20 14:32 ] | |
|
max_wedge
Joined: Aug 29, 2004
Posts: > 500
From: Australia
PM, WWW
|
michka, fair enough, I stand corrected. I was not aware wav files could contain compressed audio in mp3 format. I can see what you are saying now. It is a sort of wrapper I guess. I was just pissed cause you seemed to be missing my point and focussing on terminology, and jumping on an antimicrosoft bandwagon 
From http://encyclopedia.laborlawtalk.com/index.php(search for wav):
"Though a WAV file can hold audio compressed with any codec, by far the most common format is PCM audio data. Since PCM uses an uncompressed, lossless storage method which keeps all the samples of an audio track, professional users or audio experts may use the WAV format for maximum audio quality. WAV audio can also be edited and manipulated with relative ease using software"
Wave is a widely used for PCM.
So I get it now, but if you reread my post using 'uncompressed wave file' instead of the word 'wav' on it's own, can you tell me if I then make sense?
My point in my original post was that the file was converted into uncompressed audio then ripped to another codec.
You said "Edit: Oh and one additional thing: it is not because a PCM file (let it be wav or any other format) is not created that you don't need to go through an uncompressed PCM intermediate to transcode from mp3 to mp4. In fact you absolutely need to, but chunks of the intermediate PCM data can very well remain stored in memory. "
As a matter of fact I already understood that the "direct" conversion involves storing pcm in memory. I'm still guessing that is more complicated than ripping everything to a pcm stream first, hence my thought that that is why this type of on the fly encoding isn't available in freeware usually. Please correct me if I'm wrong, like I say I don't mind being corrected, I'm no expert.
I do know that dbpoweramp is decompressing the mp3 to a file before it encodes it to aac, was this not my original point?
Anyway, I appreciate the correction, it's all part of the learning experience. In practical use, non of the encoders I have ever used (except sndrec32, thanks for the info) have saved the file as a wave encapsulated mp3, yet all the decoders I have used to create uncompressed audio have used the wav format. |
michka
Joined: May 17, 2004
Posts: > 500
From: Brussels-Belgium
PM |
@max_edge: We do agree, the WAV word indeed refers to the definition of a standard file wrapper for sound. It defines how, where, in the file the audio data is and the properties of the data (compressed or uncompressed, the sampling rate, the bit depth of each sample etc.).
I also agree that some programs that transcode (from one compression algorithm to another compression algorithm) sound first perform a decode of the full sound length and save it as an intermediate uncompressed file, and then use this file as the input for encoding to the target compression. Whilst others do this in small consecutive sound chunks short enough that they can be stored in central memory.
Now, the WAVE word is ambiguous because some people use it instead of PCM, and others use it for WAV.
That WAV files can contain compressed sound is the reason why some people complain that their phone cannot play them: SE phones can only play PCM uncompressed WAV files.
Pedestrian: don't run, my car is faster anyway. |
max_wedge
Joined: Aug 29, 2004
Posts: > 500
From: Australia
PM, WWW
|
Awesome, thanks for the info.
From now on, it's PCM for me! |
janahan
Joined: Jan 13, 2003
Posts: 232
From: UK
PM |
Quote:
|
On 2005-03-20 18:59:15, michka wrote:
That WAV files can contain compressed sound is the reason why some people complain that their phone cannot play them: SE phones can only play PCM uncompressed WAV files.
|
|
ACTUALLY, Some SE phones (namely the Pxxx series) CAN play compressed WAV files with either the GSM or ADPCM codecs 
I know this, because i used to own a P800 before my S700i, and the P800 did not support MP3s for ringtones, so I had to compress in ADPCM to get any decent filesize for a WAV ringtone.
@colin and anyone else who misunderstands the MP3pro format.
MP3Pro is an MP3 format, with some added information that only MP3pro players will understand. If you encode a MP3pro in 64kbps you will get a normal MP3 in 64kbps with some added information for players that understaanding that added information.
playign such a file in a normal MP3 player (such as winamp, the k700/s700, ipod, etc) it will sound like a 64kbps MP3 file (actually slightly worse, since that "extra infomation" takes up some valuable space from the 64kbps stream)
Only on a MP3pro player will that extra information be processed to give a slightly better sounding sound.
Please be aware, that 64k MP3pro is STILL significantly less quality than a 64k AAC or even a 64k OggVorbis file, due to the backwards compatibility required with the MP3 format.
And on a normal MP3 player, MP3pro at 64k is less quality than MP3 at 64k. so there is no point in creating MP3pro, unless you have a MP3pro player.
I hoep this clears up the whole MP3pro shenigans |
ares
Joined: Dec 11, 2003
Posts: > 500
From: Coimbra, Portugal
PM |
Yeah, that makes all clear
SE w880 + Iphone 4 16gb |
michka
Joined: May 17, 2004
Posts: > 500
From: Brussels-Belgium
PM |
@janahan: Agreed, forgot about the P series. But non smartphones, I guess, cannot because it would imply the installation of one specific codec for each compression format.
Pedestrian: don't run, my car is faster anyway. | |
|
Access the forum with a mobile phone via esato.mobi
|
Posted: 2005-03-20 15:18
