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#1 2006-11-23 04:53:20

mccaffjt
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Registered: 2011-06-05
Posts: 1295
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Ripping: "Best" bitrate and encoder

I use "Exact Audio Copy" and the LAME encoder, with a fixed bitrate of 192K.  I can definitely hear the difference between 128K and 160K...but above 160K I don't think I hear the quality loss.  How about you?

I don't hear the difference when I go to VBR (and VBR will make smaller files), but I worry that some mp3 players don't do a great job with VBR.

My results are good, but I wondered if anyone has found anything better?

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#2 2007-07-06 18:11:34

Horst
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Registered: 2011-06-05
Posts: 6

Re: Ripping: "Best" bitrate and encoder

John, I have just ordered mp3boss, it is a great software! I use exactly the same ripping and encoding software, and I hear the quality loss up to 256k. However, you need to listen to special music with a very good headphone. Special... there are two critical sounds: applause, and big symphony orchestras. You need to listen to a very good recording of a big symphony orchestra, and a piece with loud brass passages. Normally you hear about 30 violins from the left side, with all their overtones and brilliance, and the brass section in the middle of the stereo panorama. Below 256k, as soon as the brass plays fortissimo, the sound of the violins is changed. You cannot localize the single players anymore, it sounds rather like a very good syntheziser generating a violin section sound. 256k and 320k are transparent, and the mentioned effect starts at 190k and gets worse the lower the bitrate gets. The theoretical explanation is: Because the brass is so loud, the encoder thinks that the violins are masked by the brass. However, they are not masked because they play from the left side. Because there are not enough bits used to encode the violins, the high overtones of the violins get a high phase and modulation noise. Because of that, I encode classical music with 320k and pop music with 256k. Through loudspeakers, this problem is almost imperceptible, but the headphone (AKG K240 Studio Monitor) reveals it all.
Horst

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#3 2007-07-06 20:20:13

mccaffjt
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Registered: 2011-06-05
Posts: 1295
Website

Re: Ripping: "Best" bitrate and encoder

Glad you like Mp3-Boss - feel free to spread the word...

Thanks for the information about bitrates -- I'll have to see if I can hear it too.

Do you always use fixed bitrates, or do you use VBR?

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#4 2007-07-07 16:41:50

Horst
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Registered: 2011-06-05
Posts: 6

Re: Ripping: "Best" bitrate and encoder

John, when I began to encode my complete CD collection some years ago, I read the Lame release notes and I found that while all modes were stable, most bugs found were related to the VBR mode. Furthermore there were some old MP3 players that did not support VBR, and I wanted to keep my MP3 collection usable for all purposes. Today, if I had to re-encode my CDs, I'd use Lame in a high quality VBR mode. I use RazorLame as the Lame GUI frontend, and when you encode in VBR mode, Razorlame will display a nice statistic while it encodes. Actually VBR is not totally variable. Each frame is encoded using a fixed standard bitrate (128, 160...320), but before the frame is encoded, it gets a bitrate assigned that fits its complexity. Now, when you encode with Razorlame, you will see a bar graph that shows how many percent of the frames are encoded in 320k/s, 256k/s, 192k/s, etc. One bar for each bitrate. You can see, for example, whether you have selected too low a VBR quality setting if the highest bitrate assigned is 160k/s. I would select a VBR quality setting that encodes at least 20% of the frames at 256 or 320k/s. I have made some tests, and encoding that way, I can't hear a difference between VBR and fixed bitrate.

I don't think that you have to worry about the quality of the VBR implementation in some mp3 players. As opposed to OGG, the decoding process of MP3 is deterministic: Different ENcoders will generate different MP3-files, but different DEcoders will generate identical raw data (WAV...) because each frame of the MP3 file contains 100%-clear instructions how the decoding has to be done . So if VBR is implemented, it will either work perfectly or it will fail catastrophically and well audibly. At MP3, the entire intelligence (getting the best quality at a given bitrate) is applied during the encoding process, and the resulting MP3 file does not leave any leeway for the decoder. After the MP3 encoding has finished, the quality of the resulting MP3 file is fixed, making the decoding process much easier, good for those old 486 processors it had been designed for. OGG is different, encoding and decoding need about the same processing power, and the decoder influences the quality of the playback. This symmetry (needing the same processing power during encoding and playback) is the reason why mp3 players suffer from reduced battery life if you play OGG files, and that is why I don't like OGG - the quality of the sound depends on the implementation of the OGG decoding engine of the player. At MP3, there are no good or bad decoders. They are implemented either correctly or wrong.

Horst

Last edited by Horst (2007-07-07 16:45:09)

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#5 2010-08-31 01:45:10

dennisjamison62
New member
Registered: 2011-06-05
Posts: 3

Re: Ripping: "Best" bitrate and encoder

I like mp3-boss too.....
I think almost everyone already knows about it...

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#6 2012-11-20 20:28:51

Adam Overmiller
New member
Registered: 2012-11-19
Posts: 1

Re: Ripping: "Best" bitrate and encoder

Variable bitrate (VBR) is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate (CBR), VBR files vary the amount of output data per time segment. VBR allows a higher bitrate (and therefore more storage space) to be allocated to the more complex segments of media files while less space is allocated to less complex segments. The average of these rates can be calculated to produce an average bitrate for the file.

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