Image Processing Reference
In-Depth Information
Table 38-1 Guideline Bit Rates for Video
Full size
Ordinary streamed content
70-bps stream
250-Kbps stream
500-Kbps stream
Premium streamed content
150-Kbps stream
440-Kbps stream
880-Kbps stream
Downloadable content
500-KB file
1.5-MB file
5-MB file
Downloadable movies
1-MB file
25-MB file
3.5-GB file
TV quality—SDTV MPEG-2
4-Mbps stream
TV quality—SDTV H.264
2.3-Mbps stream
TV quality—DDTV H.264
7-Mbps stream
Complexity and Motion Estimation
High complexity is sometimes presented as a parameter you can define. It is sometimes
preset and it may be called other things. Look for settings in the encoder that talk about
motion estimation or motion compensation.
Selecting a high-complexity setting in Popwire Compression Master automatically
invokes a more advanced motion-estimation algorithm, which slows down the encoding
but improves the quality of the picture. This should be especially helpful at low bit rates.
Controlling Complexity in the Decoding Process
If it is possible, we need to compress the video in such a way that it is easy for the media
player to decode. Increasing the complexity of the decoding process reduces the target
audience because more computing power is needed to run the decoder. If we can maintain
a low decode complexity coefficient, then more people with older and less powerful sys-
tems can continue to enjoy our content.
You may need to trade off compression ratio against decoding complexity to achieve
the desired balance. You would do this perhaps by limiting the use of some of the more
sophisticated compression tools that the encoder offers.
Determining which of these tools to avoid using comes down to a diligent profiling
of your target audience to establish what they are capable of decoding. Of course, this
should have happened some time before you pressed the 'OK' button on the encoder start-
up screen.
Buffer Sizing
Define the size of the buffer for the video frame if necessary. If you have access to this
parameter, it probably has different ranges of values in each encoder. Setting the encoder
to run with a small buffer might force the clip to be encoded as a constant bit rate (CBR)
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