Matrix Elements VB-800 Manual de usuario descargar pdf (Pagina 31)

Chapter 3. Advanced streaming using the command line

ﬁxed quantizer scale for VBR encodings, i-quant-factor=<quantization factor> allows to set the quantization factor of I

frames, compared to P frames, hq=<quality> allows to choose the quality level for the encoding of the motion vectors

(arguments are simple, rd or bits, default is simple *FIXME*), strict=<level of compliance> allows to force a stricter

standard compliance (possible values are -1, 0 and 1, default is 0), strict-rc enables a strict rate control algorithm,

rc-buffer-size=<size of the buffer in bits> allows to choose the size of the buffer used for rate control (bigger means

more efﬁcient rate control), rc-buffer-aggressivity=<ﬂoat representing the aggressiveness> allows to set the rate control

buffer aggressiveness *FIXME*, pre-me allows to enable pre motion estimation, mpeg4-matrix enable use of the

MPEG4 quantization matrix with MPEG2 streams, improving quality while keeping compatibility with MPEG2

decoders, trellis enables trelli quantization (better quality, but slower processing).

• theora: The Xiph.org theora encoder. The module is used to produce theora streams. Theora is a free patent and royalties

free video codec.

The only available item option is quality=<quality level>. This option allows to create a VBR stream, overriding vb

setting. the quality level must be an integer between 1 and 10. Higher is better.

• x264. x264 is a free open-source h264 encoder. h264 (or MPEG4-AVC) is a quite recent high quality video codec.

Item options are: keyint=<number of frames> allows to set the maximal amount of frames between 2 key frames,

idrint=<number of frames> allows to set the maximal amount of frames between 2 IDR frames, bframes=<amount of

frames> allows to set the amount of B frames between an I and a P frame, qp=<quantizer parameter> allows to specify

a ﬁxed quantizer (between 1 and 51), qp-max=<quantizer parameter> allows to set the maximum value for the

quantizer, qp-min=<quantizer parameter> allows to set the minimum value for the quantizer, cabac enables the

CABAC (Context-Adaptive Binary Arithmetic Coding) algorithm (slower, but enhances quality), loopﬁlter enables

deblocking loop ﬁlter, analyse enables the analyze mode, frameref=<amount of frames> allows to set the number of

previous frames used as predictors, scenecut=<sensibility< allows to control how aggressively the encoder should insert

extra I-frame, on scene change.

fps=

This options allows to set the framerate of the transcoded video, in frame per second. reducing the framerate of a video can

help decreasing its bitrate.

deinterlace

This option allows to enable deinterlacing of interlaced video streams before encoding.

croptop=

This option allows to crop the upper part of the source video while transcoding. The argument is the number of lines the

video should be cropped.

cropbottom=

This option allows to crop the lower part of the source video. The argument is the Y coordinate of the ﬁrst line to be

cropped.

cropleft

This option allows to crop the left part of the source video while transcoding. The argument is the number of columns the

video should be cropped.

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Matrix Elements VB-800 Manual de usuario Pagina 31