Grass Valley ProCoder 3 - Manual (Page 148)

14
ProCoder 3
Level
Combines with the profile, the level defines the minimum and maximum values for
the frame size, frame rate, bitrate and other settings.
GOP size
Specifies the size of a Group of Pictures. Set is to 1 to only generated I-frames. The
GOP size must be a multiple of (Number of B-frames plus one).
Number of B-frames
Specifies the number of B-frames between consecutive I and P frames. B-frames are
not allowed when the Baseline profile is selected, or if GOP size is set to 1.
Audio
Audio Compression
Specifies the type of the compression used for audio.
Bits/Sample
Specifies the file's audio sample size. The available bits per sample settings depend
on the audio encoder selected.
The number of bits per sample determines how well a particular level can be
represented. More bits per sample allows for better representation of audio changes
in the Source but results in a larger file size.
The combination of sample rate and bits per sample determine the overall quality of
the audio.
Channels
Specifies the number of channels (or channel encoding type) of audio for the Target.
Normally audio is single channel (mono) or stereo (left/right channel), but some audio
codecs allow for different encoding types such as Joint Stereo to store audio in a
more efficient manner. The options listed here depend on the audio codec used -
most codecs support Mono (1 channel) and Stereo (2 channels).
Sample Rate(kHz)
Specifies the number of audio sample per second (in thousands) for the Target. The
reproducible frequency range of the encoded audio depends on the sample rate.
Choosing a higher sample rate produces better sound quality but a larger file size. The
combination of sample rate and bits per sample determine the overall quality of the
audio. The available sample rates depend on the audio encoder selected. The higher the
sample rate, the wider the range of frequencies that can be reproduced. The maximum
reproducible frequency for a given sample rate is one-half the sample rate. For example,
a standard audio CD uses audio that is at 44.1kHz, or 44,100 samples per second (Hz),
which equates to the ability to reproduce sounds up to frequencies of 22,050 Hz.
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