class ChanCount;
+/** Multichannel Audio/Midi Delay Line
+ *
+ * This is an efficient delay line operating directly on Ardour buffers.
+ * The drawback is that there is no thread safety:
+ * All calls need to be executed in the same thread.
+ *
+ * After configuration, the delay can be changed safely up to the maximum
+ * configured delay but doing so flushes the buffer. There is no de-clicking
+ * (see ARDOUR::Delayline for those cases).
+ *
+ * Increasing the delay above the max configured or requesting more
+ * buffers will allocate the required space (not realtime safe).
+ *
+ * All buffers part of the set are treated separately.
+ */
class LIBARDOUR_API FixedDelay
{
public:
FixedDelay ();
~FixedDelay ();
- void configure (const ChanCount& count, framecnt_t);
- void set (const ChanCount& count, framecnt_t);
+ /** initial configuration, usually done after instantiation
+ *
+ * @param count Channel Count (audio+midi)
+ * @param max_delay the maximum number of samples to delay
+ * @param shrink when false already allocated buffers are kept if both channel-count and max-delay requirements are satisified
+ */
+ void configure (const ChanCount& count, framecnt_t max_delay, bool shrink = true);
+
+ /** set delay time and update active process buffers
+ *
+ * This calls configure with shrink = false and sets the current delay time
+ * if the delay time mismatches, the buffers are silenced (zeroed).
+ *
+ * @param count channels to be processed
+ * @param delay number of audio samples to delay
+ */
+ void set (const ChanCount& count, framecnt_t delay);
+
+ /** process a channel
+ *
+ * Read N samples from the input buffer, delay them by the configured delay-time and write
+ * the delayed samples to the output buffer at the given offset.
+ *
+ * @param dt datatype
+ * @param id buffer number (starting at 0)
+ * @param out output buffer to write data to
+ * @param in input buffer to read data from
+ * @param n_samples number of samples to process (must be <= 8192)
+ * @param dst_offset offset in output buffer to start writing to
+ * @param src_offset offset in input buffer to start reading from
+ */
+ void delay (ARDOUR::DataType dt, uint32_t id, Buffer& out, const Buffer& in, pframes_t n_samples, framecnt_t dst_offset = 0, framecnt_t src_offset = 0);
- void delay (ARDOUR::DataType, uint32_t, Buffer&, const Buffer&, pframes_t, framecnt_t dst_offset = 0, framecnt_t src_offset = 0);
- void flush() { _pending_flush = true; }
+ /** zero all buffers */
+ void flush();
private:
framecnt_t _max_delay;
+ framecnt_t _buf_size;
framecnt_t _delay;
- bool _pending_flush;
ChanCount _count;
struct DelayBuffer {
FixedDelay::FixedDelay ()
: _max_delay (0)
+ , _buf_size (0)
, _delay (0)
- , _pending_flush (false)
{
for (size_t i = 0; i < DataType::num_types; ++i) {
_buffers.push_back (BufferVec ());
clear ();
}
-void
-FixedDelay::configure (const ChanCount& count, framecnt_t max_delay)
-{
- if (max_delay <= _max_delay || count <= _count) {
- return;
- }
- _max_delay = std::max (_max_delay, max_delay);
- for (DataType::iterator i = DataType::begin (); i != DataType::end (); ++i) {
- ensure_buffers (*i, count.get (*i), _max_delay + 1);
- }
-}
-
-void
-FixedDelay::set (const ChanCount& count, framecnt_t delay)
-{
- configure (count, delay);
- _delay = delay;
-}
-
void
FixedDelay::ensure_buffers (DataType type, size_t num_buffers, size_t buffer_capacity)
{
_count.reset ();
}
+void
+FixedDelay::flush()
+{
+ for (std::vector<BufferVec>::iterator i = _buffers.begin (); i != _buffers.end (); ++i) {
+ for (BufferVec::iterator j = (*i).begin (); j != (*i).end (); ++j) {
+ (*j)->buf->silence (_buf_size);
+ }
+ }
+}
+
+void
+FixedDelay::configure (const ChanCount& count, framecnt_t max_delay, bool shrink)
+{
+ if (shrink) {
+ if (max_delay == _max_delay && count == _count) {
+ return;
+ }
+ _max_delay = max_delay;
+ } else if (max_delay <= _max_delay || count <= _count) {
+ return;
+ _max_delay = std::max (_max_delay, max_delay);
+ }
+
+ // max possible (with all engines and during export)
+ static const framecnt_t max_block_length = 8192;
+ _buf_size = _max_delay + max_block_length;
+ for (DataType::iterator i = DataType::begin (); i != DataType::end (); ++i) {
+ ensure_buffers (*i, count.get (*i), _buf_size);
+ }
+}
+
+void
+FixedDelay::set (const ChanCount& count, framecnt_t delay)
+{
+ configure (count, delay, false);
+ if (_delay != delay) {
+ flush ();
+ }
+ _delay = delay;
+}
+
void
FixedDelay::delay (
ARDOUR::DataType dt, uint32_t id,
assert (id < _buffers[dt].size ());
DelayBuffer *db = _buffers[dt][id];
- if (db->pos + n_frames > _max_delay) {
- uint32_t w0 = _max_delay - db->pos;
- uint32_t w1 = db->pos + n_frames - _max_delay;
+ if (db->pos + n_frames > _buf_size) {
+ uint32_t w0 = _buf_size - db->pos;
+ uint32_t w1 = db->pos + n_frames - _buf_size;
db->buf->read_from (in, w0, db->pos, src_offset);
db->buf->read_from (in, w1, 0, src_offset + w0);
} else {
db->buf->read_from (in, n_frames, db->pos, src_offset);
}
- uint32_t rp = (db->pos + _max_delay - _delay) % _max_delay;
+ uint32_t rp = (db->pos + _buf_size - _delay) % _buf_size;
- if (rp + n_frames > _max_delay) {
- uint32_t r0 = _max_delay - rp;
- uint32_t r1 = rp + n_frames - _max_delay;
+ if (rp + n_frames > _buf_size) {
+ uint32_t r0 = _buf_size - rp;
+ uint32_t r1 = rp + n_frames - _buf_size;
out.read_from (*db->buf, r0, dst_offset, rp);
out.read_from (*db->buf, r1, dst_offset + r0, 0);
} else {
out.read_from (*db->buf, n_frames, dst_offset, rp);
}
- db->pos = (db->pos + n_frames) % _max_delay;
+ db->pos = (db->pos + n_frames) % _buf_size;
}
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