* The stride parameter is ignored.
*/
AV_TX_FLOAT_FFT = 0,
+
/**
* Standard MDCT with sample data type of float and a scale type of
* float. Length is the frame size, not the window size (which is 2x frame)
* For forward transforms, the stride specifies the spacing between each
* sample in the output array in bytes. The input must be a flat array.
+ *
* For inverse transforms, the stride specifies the spacing between each
* sample in the input array in bytes. The output will be a flat array.
* Stride must be a non-zero multiple of sizeof(float).
+ *
* NOTE: the inverse transform is half-length, meaning the output will not
- * contain redundant data. This is what most codecs work with.
+ * contain redundant data. This is what most codecs work with. To do a full
+ * inverse transform, set the AV_TX_FULL_IMDCT flag on init.
*/
AV_TX_FLOAT_MDCT = 1,
+
/**
* Same as AV_TX_FLOAT_FFT with a data type of AVComplexDouble.
*/
AV_TX_DOUBLE_FFT = 2,
+
/**
* Same as AV_TX_FLOAT_MDCT with data and scale type of double.
* Stride must be a non-zero multiple of sizeof(double).
*/
AV_TX_DOUBLE_MDCT = 3,
+
/**
* Same as AV_TX_FLOAT_FFT with a data type of AVComplexInt32.
*/
AV_TX_INT32_FFT = 4,
+
/**
* Same as AV_TX_FLOAT_MDCT with data type of int32_t and scale type of float.
* Only scale values less than or equal to 1.0 are supported.
* @param stride the input or output stride in bytes
*
* The out and in arrays must be aligned to the maximum required by the CPU
- * architecture.
+ * architecture unless the AV_TX_UNALIGNED flag was set in av_tx_init().
* The stride must follow the constraints the transform type has specified.
*/
typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
+/**
+ * Flags for av_tx_init()
+ */
+enum AVTXFlags {
+ /**
+ * Performs an in-place transformation on the input. The output argument
+ * of av_tn_fn() MUST match the input. May be unsupported or slower for some
+ * transform types.
+ */
+ AV_TX_INPLACE = 1ULL << 0,
+
+ /**
+ * Relaxes alignment requirement for the in and out arrays of av_tx_fn().
+ * May be slower with certain transform types.
+ */
+ AV_TX_UNALIGNED = 1ULL << 1,
+
+ /**
+ * Performs a full inverse MDCT rather than leaving out samples that can be
+ * derived through symmetry. Requires an output array of 'len' floats,
+ * rather than the usual 'len/2' floats.
+ * Ignored for all transforms but inverse MDCTs.
+ */
+ AV_TX_FULL_IMDCT = 1ULL << 2,
+};
+
/**
* Initialize a transform context with the given configuration
* (i)MDCTs with an odd length are currently not supported.
* @param inv whether to do an inverse or a forward transform
* @param len the size of the transform in samples
* @param scale pointer to the value to scale the output if supported by type
- * @param flags currently unused
+ * @param flags a bitmask of AVTXFlags or 0
*
* @return 0 on success, negative error code on failure
*/