Добавлено: 12.05.2008 | Размер: 1.8 Мб
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Особенности HC 0.22:
HC is a 2 pass encoder which produces a VBR MPEG2 stream. Bitrate control is controlled by an average bitrate value and a maximum bitrate value.
- Bit Rate control
Bit rate is controlled by two commands: *BITRATE and *MAXBITRATE. Buffer underflows will never occur, while encoding the frames, the VBV (Video Buffer Verifier) is constantly checked for buffer underruns, if buffer underruns occur the bit stream will be adapted so the stream will always be DVD-compliant.
- Encoding quality
Encoding quality is controlled by the encoding profile: FAST, NORMAL, BEST. For the *PROFILE command, see the command section.
- GOP structure
User controllable, maximum GOP length is 36, maximum consecutive B-pictures is 2.
You can for instance give the command *GOP 15 2 or *GOP 12 1, see the command section. If the *GOP command is omitted, HC wil run in AUTOGOP mode, this probably is the best way to run the encoder. In AUTOGOP mode HC scans frames to be encoded and measures the activity of the frames. Based on the activity of the frames HC tries to create an optimal GOP structure. A sequence header is written for each GOP.
- Scene change detection
HC has a scene change detection algorithm built in, on each scene detection an I-frame is inserted and the GOP will be closed so you can cut the video at each scene change. If necessary the frames in the two previous GOP's will be redistributed to maintain a nice general GOP structure.
HC has a *RESTART option (see the command section) to re-run the second pass (GUI version
only). It's required that the database file (.dbs) is still present because it contains all the necessary information to run the second pass again.
You can not change every command during a restart, for instance the GOP structure as calculated in the first pass is fixed and can not be changed. If you do a restart the database will be scanned for info to do the second pass, this might take approx. 1 minute for a whole movie depending on the speed of your system. See the command section for further information.
- Quantization matrices
You can use any matrix you like, some well known matrices are already built in which can be activated by the *MATRIX command. If you want to use your own matrix (intra and non-intra) just give the command *CUSTOMMATRIX and specify the two matrices, see the command section. If the *MATRIX command is omitted HC will use the standard “adapted” MPEG matrices, see the matrix section for these matrix specifications.
- Encoding speed
Encoding speed is highly dependent of:
* Complexity of the video material
* Speed of your system: CPU, cache size and memory speed
* Availability of CPU extensions
A fast system will encode a 2 hour movie (DVD backup) in approx. 2.5 hours, 1.5 hours for the first pass and 1 hour for the second pass with *PROFILE BEST.
Encoding (interlaced) DV video might take longer to encode.