The UMSRTV2Encoder object provides methods to compress video frames to the RTV 2.1 image format. It is presented in the class library for editing and format conversion purposes.
To learn more about the UMSRTV2Encoder object, see:
For introductory information, see Video Codec Objects.
To avoid name collision on defines, integer values have been captured as enumerated lists. The set of valid values from an enumerated list varies with the application. The detailed method descriptions describe the valid or possible values for the specific use. The enumerated lists that are defined for this object are listed below.
enum ReturnCode {
Success,
Failure,
UnsupportedFormat,
UnsupportedAlgorithm,
OutOfRange,
Uninitialized,
OutOfMemory
}
enum ImageFormatIn {
YUV9,
RGB24
}
enum FrameType {
Reference,
PeriodRef
Delta
}
enum Scale {
Full,
Half
}
The UMSRTV2Encoder object defines the following types:
This method sets the format of the input frames that the encoder expects. If an invalid format is specified, then the method returns the error code UnsupportedFormat; otherwise, the method returns Success.
| in ImageFormatIn rtv2_enc_image_format | Specifies the format of the input image. |
Queries the current input image format. It always returns Success.
| inout ImageFormatIn rtv2_enc_image_format | The current setting of the input image format. |
This method sets the frame width and height parameters, and mallocs the internal frame buffers for the UMSRTV2Encoder object. If either of the input dimensions is not a multiple of 8, the method sets up the encoder to encode a subframe of each input frame. The subframe starts at the top left corner of the input frame, and has dimensions that are multiples of 8. If either of the requested dimensions is negative or greater than 4096, the method returns OutOfRange. If a malloc fails, the method returns OutOfMemory. Otherwise, it returns Success.
| in long width | Width of the input frame. |
| in long height | Height of the input frame. |
Queries the frame width and height parameters. It always returns Success.
| inout long width | Current setting of the frame width. |
| inout long height | Current setting of the frame height. |
This method sets the position and size of the subimage of the input frame that should be encoded. It truncates the subframe width and height to multiples of 8. The position parameters refer to the top left corner of the subframe; (0, 0) refers to the top left corner of the full input frame.
This method queries the subimage size and position parameters. If set_subimage_size has not been called, these have the default values; otherwise, they have the values set by the last call to set_subimage_size.
This method sets the flags that control subsampling of the input before the actual compression; RTV allows for subsampling by 2:1 in either or both directions before compression. This method also (re-)mallocs the image buffers.
| in Scale xscale | Specifies full or half image size in the x dimension. |
| in Scale yscale | Specifies full or half image size in the y dimension. |
Queries the current settings for the scaling in the x and y dimension.
| inout Scale xscale | Specifies full or half image size in the x dimension. |
| inout Scale yscale | Specifies full or half image size in the y dimension. |
This method returns an upper limit on the size of the output buffer for the encoder. The application should use this size to malloc a buffer to receive the compressed frames. The size depends on the dimensions of the input frames.
| inout long buffer_size | The maximum size of a compressed image. |
This method compresses an input frame with bitrate control. First, the method compresses the frame with the initial_quality_factor setting. If the size of the compressed frame in bytes is less than or equal to the length parameter, the method returns. Otherwise, the method decreases the internal quality level and recompresses the frame until the size of the compressed frame is less than or equal to the length parameter. After compressing the frame for the last time, the method computes a final_quality_factor.
If the initial_quality_factor is less than 0 or greater than 100, or if the length parameter is not positive, the method returns OutOfRange. Otherwise, the method behaves similarly to the compress_frame_QF method.
This method compresses an input frame according to a requested quality and frame type. The frame types are Reference and Delta; the quality factor can vary between 0 and 100.
If the requested frame type is Delta, the encoder first compares the input frame to its internal copy of the previous reconstructed (compressed/decompressed) frame. If the difference is large, the encoder switches the variable frame_type to Reference for the current frame. This occurs where there are scene changes or fast motion.
For introductory information, see Video Codec Objects.