3ivx MPEG-4 5.0.4 - Mac OS - QuickTime Compression Settings


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3ivx QuickTime Video Codec
Compression Settings

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		Basic Options Encoder Modes: Single Pass - Constant Quality Single Pass - Average Bitrate Single Pass - Constant Bitrate Dual Pass - First Pass Dual Pass - Second Pass Best Quality for Bitrate Constant Bitrate for Streaming Advanced Options Force keyframe after XXX delta frames Speed vs Quality Half Pixel Motion Four Vector Motion Quantizer Pure MP4s NVops Qpel Adaptive Quantization Bframes
		Single Pass - Constant Quality (CQ) Encodes the video in a single pass with a fixed quality. The quality is defined via a QP value. The QP (or Quantization Parameter) allows direct configuration of the video QP used. A lower QP will result in better video quality with a larger file. A Higher QP will result in lower video quality, more compression and a smaller file. The valid range for a QP in MPEG-4 is 1..31. QP=1 is normally excessive, although it does produce near lossless video. QP2 is a recommended maximum quality. QP31 is excessively low quality producing almost total blocking, as the gains after QP22 are normally limited a recommended minimum quality is QP22 Video size can not be adequately controlled or predicted when using Constant Quality mode, although quality can be. Constant Quality encoding is not suitable for streaming.

		Single Pass - Average Bitrate (ABR) Encodes the video in a single pass aiming to maintain an average bitrate. The algorithm is quite clever but can not produce the stunning video results which a dual-pass algorithm can because the encoder has no idea what video conditions will present themselves in the future. The algorithm is controlled by the Average Bitrate setting, which is in Kilobytes/Second. The bitrate can be entered in the 'Limit data rate to ... KBytes/sec' field in the 'Compression Settings' dialog from QuickTime. (Bitrate Calculator) The Maximum and Minimum Quality is used for ABR encoding, but normally the default QPs (2..22) would be the correct setting. ABR encoding will be suitable for most forms of streaming, but is not a pure Constant Bitrate algorithm. *Maximum Quality (Minimum Quantizer)* The minimum Quantization Parameter to use during encoding. The lower the number the higher the maximum quality. Lowering the Minimum Quantizer will make the encoder more conservative. Valid values are 1..31. *Minimum Quality (Maximum Quantizer)* The maximum Quantization Parameter to use during encoding. The higher the number the lower the minimum quality. If the Maximum Quantizer is too low, the encoder may overshoot the specified bitrate. Valid values are 2..31.
		Single Pass - Constant Bitrate (CBR) The constant bitrate mode will react quickly on bitrate spikes, lowering the image quality of the video and dropping frames if necessary. This is ideal for Live Broadcasting and Video Conferencing where the maximum quality in an instantaneous constant bitrate is the most important concern. The bitrate can be entered in the 'Limit data rate to ... KBytes/sec' field in the 'Compression Settings' dialog from QuickTime. (Bitrate Calculator) *Maximum Quality (Minimum Quantizer)* The minimum Quantization Parameter to use during encoding. The lower the number the higher the maximum quality. Increasing the Minimum Quantizer will make the encoder more conservative. Valid values are 1..31. *Minimum Quality (Maximum Quantizer)* The maximum Quantization Parameter to use during encoding. The higher the number the lower the minimum quality. Raising the Maximum Quantizer may cause the encoder to drop more frames. Valid values are 1..31.
		What is Dual Pass? Dual Pass encoding allows the encoder to produce the best possible video by performing two passes during encoding. On the first pass the encoder analyzes the video and collects detailed statistics. On the second pass the encoder uses the statistics from the first pass to make better coding decisions and to distribute the bitrate appropriately over the entirety of the video clip. After the first pass encode you may do as many second pass encodes as necessary (i.e. at different bitrates). It is important to not change the video framerate or resolution between passes. The source video and Advanced Options must be the same for both passes.
		Dual Pass - First Pass The Log File is where the statistics will be recorded in the first pass and read from in the second pass If you will be encoding more than one video at the same time remember to use a different log file for each video. You can choose to output video in the first pass, but as the encoded video will be large, video output is normally disabled to avoid filling a users hard drive.

		Dual Pass - Second Pass A Log file was recorded during the First Pass and must be selected. *Dual Pass - Best Quality for Bitrate* Dual Pass Best Quality encoded video will normally have the best quality and most accurate bitrate. The encoder attempts to find the highest possible average quality and encodes the video to maintain that quality. *Dual Pass - Constant Bitrate for Streaming* Dual Pass Constant Bitrate encoding allows the encoder to produce video as close as possible to a Constant Bitrate by performing two passes during encoding. The average bitrate will sometimes be less than requested because the encoder will not accumulate gains from frames which did not require the full constant bitrate. This is to enable successful streaming. Credit Suppresion is not available for Constant Bitrate encoding. The bitrate can be entered in the 'Limit data rate to ... KBytes/sec' field in the 'Compression Settings' dialog from QuickTime. (Bitrate Calculator) *Suppress last ... frames to ... %* The specified frames (counted from the end) will be encoded at a lower bitrate (based on the Suppresion Ratio). This can be used for encoding credits, which traditionally use a lot of bits. *Suppresion Ratio* The suppresion ratio specifies the final size of the suppresed frames relative to what they would normally be. Lower percentages result in smaller credits and 100% effectively disables credit suppresion.
		Advanced Options - Encoding Features Advanced Options can result in poor performace or results if used incorrectly. *Force keyframe after ... delta frames* In normal operation the encoder will insert keyframes for scene changes or where a keyframe would result in a more efficient encode. But in order to promote random access it is sometimes necessary to insert keyframes more regularly. The codec will insert a keyframe if it has outputted this many non-keyframes in a row. By setting this value to 0 you can produce an all keyframe video, which could be usefull for an editing format, similar to DV. Keyframes are also usefull for streaming broadcasts, as a user can normally only begin watching a stream after receiving a keyframe, if the stream was 25fps, and keyframes were only inserted after 250 frames (worst case) then the user might have to wait 10 seconds before seeing the stream (worst case). 300 is the default value for normal video tasks, for streaming we recommend a keyframe every 5 seconds (fps times 5). Speed vs Quality Half Pixel Motion If checked the codec will perform half pixel precision motion search. Half Pixel motion dramatically increases quality and codec efficiency in almost all cases. Disabling Half Pixel Motion can speed up an encode. *Four Vector Motion* If checked the codec will perform 8x8 block search as well as 16x16 block matching resulting in 4 motion vectors for some 16x16 blocks. This can improve the motion representation, thus improving quality and reducing bitrate. Disabling Four Vector Motion can speed up an encode. *Quantizer* Different Quantizers can be used when compressing video. The default Quantizer is the H.263 Quantizer, and results in good compression with a mild smoothing of the image. The MPEG-4 alternative Quantizer produces videos which are normally slightly sharper, but can exhibit blocking artifacts at high QPs and will normally require more bitrate. MPEG Quantization is not part of the Simple Profile and thus will force the output of Advanced Simple Profile video. Advanced Simple Profile video in an MP4 file can not be opened by a Simple Profile Decoder, like QuickTime 6. Custom Quantizer (ASP) is similar to the MPEG Quantizer except that custom Inter and Intra quantization matrices can be specified using the 'Customize Matrix...' button. Custom Matrices are an expert setting and beyond the scope of this documentation. More... Pure MP4 When enabled 3ivx MPEG-4 5.0.1 generates video that is 100% ISO Pure MP4 compatible and will not work with some AVI based tools. Pure MP4 is not required to be compatible with QuickTime 6 or 7's built-in MPEG-4 support. NVops NVop Coding is an Efficient method of coding dropped or duplicate frames. The effect is most noticable when enabled in low bitrate encodes. The NVop Coding Technique is MPEG-4 Compliant, however it is not supported by Apple's MPEG-4 Stream Hinter. Qpel Quarter Pixel (QPel) motion compensation can increase effeciency by more precisely describing intra-frame motion. This is typically offset by the increased constant bitstream overhead of running a higher level of description. Therefore, enabling QPEL does not typically produce smaller file sizes. However, since QPEL delivers sharper images, an equivalent sized QPEL enabled file, will generally be perceived as offering higher visual quality, than a non QPEL file. *Adaptive Quantization* A feature which can dramatically improve the efficiency of the codec (resulting in smaller files which look better) by varying the quantization of the video on a block by block basis based on perceptual cues. Adaptive Quantization works best with Constant Quality encoding to reduce the file size without dramatically reducing the quality. Adaptive Quantization also works well with Single Pass bitrate controlled encodes (CBR and ABR). During a Dual Pass encode the Adaptive Quantization setting has no effect. Bframes Selecting 'Bframes', turns on creation of Bframes during encoding. This can sometimes result in greater efficiency.

Support > Mac OS > Encoding > Compression Settings