On 1/12/2021 4:18 AM, Lynne wrote:
This patch adds support for arbitrary-point FFTs and all even MDCT
transforms.
Odd MDCTs are not supported yet as they're based on the DCT-II and DCT-III
and they're very niche.
With this we can now write tests.
Patch attached.
[...]
@@ -575,11 +651,13 @@ int TX_NAME(ff_tx_init_mdct_fft)(AVTXContext *s, av_tx_fn
*tx,
const void *scale, uint64_t flags)
{
const int is_mdct = ff_tx_type_is_mdct(type);
- int err, n = 1, m = 1, max_ptwo = 1 << (FF_ARRAY_ELEMS(fft_dispatch) - 1);
+ int err, l, n = 1, m = 1, max_ptwo = 1 << (FF_ARRAY_ELEMS(fft_dispatch) -
1);
if (is_mdct)
len >>= 1;
+ l = len;
+
#define CHECK_FACTOR(DST, FACTOR, SRC)
\
if (DST == 1 && !(SRC % FACTOR)) {
\
DST = FACTOR;
\
@@ -601,12 +679,23 @@ int TX_NAME(ff_tx_init_mdct_fft)(AVTXContext *s, av_tx_fn
*tx,
s->inv = inv;
s->type = type;
- /* Filter out direct 3, 5 and 15 transforms, too niche */
+ /* If we weren't able to split the length into factors we can handle,
+ * resort to using the naive and slow FT. This also filters out
+ * direct 3, 5 and 15 transforms as they're too niche. */
if (len > 1 || m == 1) {
- av_log(NULL, AV_LOG_ERROR, "Unsupported transform size: n = %i, "
- "m = %i, residual = %i!\n", n, m, len);
- return AVERROR(EINVAL);
- } else if (n > 1 && m > 1) { /* 2D transform case */
+ if (is_mdct && (l & 1)) /* Odd (i)MDCTs are not supported yet */
+ return AVERROR(ENOTSUP);
I think ENOTSUP is not portable, which is why we use ENOSYS to signal
unimplemented/unsupported features.
+ s->n = l;
+ s->m = 1;
+ *tx = naive_fft;
+ if (is_mdct) {
+ s->scale = *((SCALE_TYPE *)scale);
+ *tx = inv ? naive_imdct : naive_mdct;
+ }
+ return 0;
+ }
+
+ if (n > 1 && m > 1) { /* 2D transform case */
if ((err = ff_tx_gen_compound_mapping(s)))
return err;
if (!(s->tmp = av_malloc(n*m*sizeof(*s->tmp))))
--
2.30.0.rc2
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