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When you select WMA output format and press Custom profile... button
in Output format section on main program window, you will get dialog window shown below.
By changing various WMA format settings in this dialog you can create your custom profile, which
can be saved and used to set up conversions in Batch List later.
Filter.
There are a lot of format variations
for each encoding method in WMA codec and sometimes
it's really hard to scroll through all available formats to find one
you need. Group of controls on top of this dialog window helps you to set up restrictions
to decrease number of formats shown. (only formats matching restrictions will be shown)
- Channels
Here you can set restriction on number of channels supported in
codec format, available options are: Mono, 2 Channels (Stereo),
5.1 Channels and 7.1 Channels. Only those formats which support
given number of channels will be displayed in Format list.
- Bits per sample
Here you can set restriction on number of bits per sample supported
in codec format, available options are: 16 bits per sample and
24 bits per sample. Only those formats which support given number
of bits per sample will be displayed
in Format list.
- Min sample rate
Here you can set restriction on sample rate supported in
codec format, available options are: 8000Hz, 11025Hz, 16000Hz,
22050Hz, 32000Hz, 44100Hz, 48000Hz, 88200Hz and 96000Hz. Only those
formats which support sample rate equal or greater than given value
will be displayed in Format list.
- Max sample rate
Here you can set restriction on sample rate supported in
codec format, available options are: 8000Hz, 11025Hz, 16000Hz,
22050Hz, 32000Hz, 44100Hz, 48000Hz, 88200Hz and 96000Hz. Only those
formats which support sample rate equal or less than given value
will be displayed in Format list.
Encoding method.
There are five encoding methods available in WMA audio format:
- 1-pass Constant Bit Rate (CBR)
The main advantage of CBR encoding
is that the bit rate and size of the encoded stream are known prior
to encoding. For example, if you are encoding a three minute song
at 32,000 bits per second, you know that the file size will be
about 704 kilobytes (32,000 bps x 180 seconds / 8 bits per byte / 1,024).
You also know that the bandwidth required to stream the encoded content is about 32,000 bits per second.
The disadvantage of CBR encoding
is that the quality of the encoded content will not be constant.
Because some content is more difficult to compress than others,
parts of a CBR stream will be of lower quality than others.
CBR encoding will also result in inconsistent
quality from one file to the next. If you use CBR
to encode several songs of different genres at the same bit rate,
you will probably notice some difference in the level of quality
In general, variations in the quality of a CBR
file will be more pronounced at lower bit rates. At higher bit
rates, the quality of a CBR encoded
file will still vary, but the quality issues will be less noticeable
to the user. When using CBR encoding, you should set the bandwidth as high as your delivery
scenario allows.
- 2-pass CBR
When you use two-pass encoding, the codec processes all of the samples
for the stream twice. On the first pass, the codec gathers information
about the content of the stream. On the second pass, the codec
uses the information gathered on the first pass to optimize the
encoding process for the stream.
In the CBR encoding mode, files that are encoded in two passes are generally
more efficient than files encoded in a single pass.
- Quality based Variable Bit Rate (VBR)
The first type of VBR encoding is quality-based, which uses one encoding
pass. Quality based VBR encoding enables you to specify a level
of quality for a digital media stream instead of a bit rate. The
codec will then encode the content so that all samples are of comparable
quality.
The main advantage of quality-based VBR encoding is that quality is consistent
within a file and from one file to the next. For example, you can
write a program to copy songs from CD to ASF files on a computer.
In this case, consistent quality is probably more important to the
end-user experience than consistent file size. Using quality-based
VBR encoding would ensure that all of the songs copied are of the
same quality.
The disadvantage of quality-based VBR encoding is that there is really no way to
know the size or bandwidth requirements of the encoded media before
encoding. This can make quality-based VBR-encoded files inappropriate
for circumstances where memory or bandwidth are
restricted, such as portable media players, or low-bandwidth Internet
connections.
In general, quality-based VBR encoding is well suited for local playback or high bandwidth
network connections. In those cases, the consistent quality will
provide a better user experience.
- Bit rate based VBR
When you use two-pass encoding, the codec will process all of the samples
for the stream twice. On the first pass, the codec gathers information
about the content of the stream. On the second pass, the codec uses
the information gathered on the first pass to optimize the encoding
process for the stream.
When using 2-pass VBR encoding, you specify a bit rate for the
stream, as you would with CBR encoding.
Unlike CBR, however, the
codec will use this value as the average bit rate for the stream
and will encode so that the quality is as high as possible while
maintaining the average. The actual bit rate at any point in
the encoded stream can vary greatly from the average value.
In general, files that are encoded in two passes are much more efficient than
files encoded in a single pass. The advantage of 2-pass VBR encoding
is that the compressed stream will have the highest possible quality
while staying within a predictable average bandwidth.
- Lossless VBR
This
type of conversion compress audio content without quality
loss, it means that audio content decompressed from Lossless
audio is mathematically identical to original.
Lossless audio, in such a way, is useful for audio CD
collection backup, but such a backup may take a lot of your hard
drive space.
Set maximum bitrate
Here you can set restriction for maximum bit rate value,
only available if you are using Bit rate based VBR encoding
method.
Save profile as:
Here you can write down name for your new profile. When you are done with
this dialog, press "OK" button and this set of options will
be saved with given name for future use.
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