codec: Add hint for real-time devices (e.g. sound cards).

Author: bmc0

alsa.c

@@ -293,6 +293,7 @@ struct codec * alsa_codec_init(const struct codec_params *p)
 	c->prec = enc_info->prec;
 	if (enc_info->can_dither) c->hints |= CODEC_HINT_CAN_DITHER;
 	if (p->mode == CODEC_MODE_WRITE) c->hints |= CODEC_HINT_INTERACTIVE;
+	c->hints |= CODEC_HINT_REALTIME;
 	c->buf_ratio = buf_frames / p->block_frames;
 	c->frames = -1;
 	if (p->mode == CODEC_MODE_READ) c->read = alsa_read;

ao.c

@@ -1,7 +1,7 @@
 /*
  * This file is part of dsp.
  *
- * Copyright (c) 2014-2024 Michael Barbour <[email protected]>
+ * Copyright (c) 2014-2025 Michael Barbour <[email protected]>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -150,6 +150,7 @@ struct codec * ao_codec_init(const struct codec_params *p)
 	c->prec = enc_info->prec;
 	c->hints |= CODEC_HINT_CAN_DITHER;  /* all formats are fixed-point LPCM */
 	c->hints |= CODEC_HINT_INTERACTIVE;
+	c->hints |= CODEC_HINT_REALTIME;
 	c->buf_ratio = p->buf_ratio;
 	c->frames = -1;
 	c->write = ao_write;

codec.h

@@ -37,6 +37,7 @@ enum {
 	CODEC_HINT_INTERACTIVE = 1<<0,
 	CODEC_HINT_CAN_DITHER  = 1<<1,
 	CODEC_HINT_NO_OUT_BUF  = 1<<2,
+	CODEC_HINT_REALTIME    = 1<<3,
 };
 
 struct codec {

dsp.c

@@ -533,7 +533,7 @@ static ssize_t do_seek(struct codec *in, ssize_t pos, ssize_t offset, int whence
 	}
 	if ((s = in->seek(in, s)) >= 0) {
 		reset_effects_chain(&chain);
-		codec_write_buf_drop(out_codec_buf, pause_state, pause_state);
+		codec_write_buf_drop(out_codec_buf, pause_state || (in->hints & CODEC_HINT_REALTIME), pause_state);
 		return s;
 	}
 	return pos;

pulse.c

@@ -1,7 +1,7 @@
 /*
  * This file is part of dsp.
  *
- * Copyright (c) 2014-2024 Michael Barbour <[email protected]>
+ * Copyright (c) 2014-2025 Michael Barbour <[email protected]>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -163,6 +163,7 @@ struct codec * pulse_codec_init(const struct codec_params *p)
 	c->prec = enc_info->prec;
 	if (enc_info->can_dither) c->hints |= CODEC_HINT_CAN_DITHER;
 	if (p->mode == CODEC_MODE_WRITE) c->hints |= CODEC_HINT_INTERACTIVE;
+	c->hints |= CODEC_HINT_REALTIME;
 	c->buf_ratio = p->buf_ratio;
 	c->frames = -1;
 	if (p->mode == CODEC_MODE_READ) c->read = pulse_read;