apps/plugins/mpegplayer/pcm_output.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * PCM output buffer definitions
  11  *
  12  * Copyright (c) 2007 Michael Sevakis
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License
  16  * as published by the Free Software Foundation; either version 2
  17  * of the License, or (at your option) any later version.
  18  *
  19  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  20  * KIND, either express or implied.
  21  *
  22  ****************************************************************************/
  23 #include "plugin.h"
  24 #include "mpegplayer.h"
  25
  26 /* Pointers */
  27
  28 /* Start of buffer */
  29 static struct pcm_frame_header * ALIGNED_ATTR(4) pcm_buffer;
  30 /* End of buffer (not guard) */
  31 static struct pcm_frame_header * ALIGNED_ATTR(4) pcmbuf_end;
  32 /* Read pointer */
  33 static struct pcm_frame_header * ALIGNED_ATTR(4) pcmbuf_head IBSS_ATTR;
  34 /* Write pointer */
  35 static struct pcm_frame_header * ALIGNED_ATTR(4) pcmbuf_tail IBSS_ATTR;
  36
  37 /* Bytes */
  38 static ssize_t  pcmbuf_curr_size IBSS_ATTR; /* Size of currently playing frame */
  39 static ssize_t  pcmbuf_read      IBSS_ATTR; /* Number of bytes read by DMA */
  40 static ssize_t  pcmbuf_written   IBSS_ATTR; /* Number of bytes written by source */
  41 static ssize_t  pcmbuf_threshold IBSS_ATTR; /* Non-silence threshold */
  42
  43 /* Clock */
  44 static uint32_t clock_start  IBSS_ATTR; /* Clock at playback start */
  45 static uint32_t volatile clock_tick IBSS_ATTR; /* Our base clock */
  46 static uint32_t volatile clock_time IBSS_ATTR; /* Timestamp adjusted */
  47
  48 static int pcm_skipped = 0;
  49 static int pcm_underruns = 0;
  50
  51 /* Small silence clip. ~5.80ms @ 44.1kHz */
  52 static int16_t silence[256*2] ALIGNED_ATTR(4) = { 0 };
  53
  54 /* Delete all buffer contents */
  55 static void pcm_reset_buffer(void)
  56 {
  57     pcmbuf_threshold = PCMOUT_PLAY_WM;
  58     pcmbuf_curr_size = pcmbuf_read = pcmbuf_written = 0;
  59     pcmbuf_head = pcmbuf_tail = pcm_buffer;
  60     pcm_skipped = pcm_underruns = 0;
  61 }
  62
  63 /* Advance a PCM buffer pointer by size bytes circularly */
  64 static inline void pcm_advance_buffer(struct pcm_frame_header **p,
  65                                       size_t size)
  66 {
  67     *p = SKIPBYTES(*p, size);
  68     if (*p >= pcmbuf_end)
  69         *p = SKIPBYTES(*p, -PCMOUT_BUFSIZE);
  70 }
  71
  72 /* Return physical space used */
  73 static inline ssize_t pcm_output_bytes_used(void)
  74 {
  75     return pcmbuf_written - pcmbuf_read; /* wrap-safe */
  76 }
  77
  78 /* Return physical space free */
  79 static inline ssize_t pcm_output_bytes_free(void)
  80 {
  81     return PCMOUT_BUFSIZE - pcm_output_bytes_used();
  82 }
  83
  84 /* Audio DMA handler */
  85 static void get_more(unsigned char **start, size_t *size)
  86 {
  87     ssize_t sz;
  88
  89     /* Free-up the last frame played frame if any */
  90     pcmbuf_read += pcmbuf_curr_size;
  91     pcmbuf_curr_size = 0;
  92
  93     sz = pcm_output_bytes_used();
  94
  95     if (sz > pcmbuf_threshold)
  96     {
  97         pcmbuf_threshold = PCMOUT_LOW_WM;
  98
  99         while (1)
 100         {
 101             uint32_t time = pcmbuf_head->time;
 102             int32_t offset = time - clock_time;
 103
 104             sz = pcmbuf_head->size;
 105
 106             if (sz < (ssize_t)(PCM_HDR_SIZE + 4) ||
 107                 (sz & 3) != 0)
 108             {
 109                 /* Just show a warning about this - will never happen
 110                  * without a corrupted buffer */
 111                 DEBUGF("get_more: invalid size (%ld)\n", (long)sz);
 112             }
 113
 114             if (offset < -100*CLOCK_RATE/1000)
 115             {
 116                 /* Frame more than 100ms late - drop it */
 117                 pcm_advance_buffer(&pcmbuf_head, sz);
 118                 pcmbuf_read += sz;
 119                 pcm_skipped++;
 120                 if (pcm_output_bytes_used() > 0)
 121                     continue;
 122
 123                 /* Ran out so revert to default watermark */
 124                 pcmbuf_threshold = PCMOUT_PLAY_WM;
 125                 pcm_underruns++;
 126             }
 127             else if (offset < 100*CLOCK_RATE/1000)
 128             {
 129                 /* Frame less than 100ms early - play it */
 130                 *start = pcmbuf_head->data;
 131
 132                 pcm_advance_buffer(&pcmbuf_head, sz);
 133                 pcmbuf_curr_size = sz;
 134
 135                 sz -= PCM_HDR_SIZE;
 136
 137                 *size = sz;
 138
 139                 /* Audio is time master - keep clock synchronized */
 140                 clock_time = time + (sz >> 2);
 141
 142                 /* Update base clock */
 143                 clock_tick += sz >> 2;
 144                 return;
 145             }
 146             /* Frame will be dropped - play silence clip */
 147             break;
 148         }
 149     }
 150     else
 151     {
 152         /* Ran out so revert to default watermark */
 153         if (pcmbuf_threshold == PCMOUT_LOW_WM)
 154             pcm_underruns++;
 155
 156         pcmbuf_threshold = PCMOUT_PLAY_WM;
 157     }
 158
 159     /* Keep clock going at all times */
 160     *start = (unsigned char *)silence;
 161     *size = sizeof (silence);
 162
 163     clock_tick += sizeof (silence) / 4;
 164     clock_time += sizeof (silence) / 4;
 165
 166     if (sz < 0)
 167         pcmbuf_read = pcmbuf_written;
 168 }
 169
 170 /** Public interface **/
 171
 172 /* Return a buffer pointer if at least size bytes are available and if so,
 173  * give the actual free space */
 174 unsigned char * pcm_output_get_buffer(ssize_t *size)
 175 {
 176     ssize_t sz = *size;
 177     ssize_t free = pcm_output_bytes_free() - PCM_HDR_SIZE;
 178
 179     if (sz >= 0 && free >= sz)
 180     {
 181         *size = free; /* return actual free space (- header) */
 182         return pcmbuf_tail->data;
 183     }
 184
 185     /* Leave *size alone so caller doesn't have to reinit */
 186     return NULL;
 187 }
 188
 189 /* Commit the buffer returned by pcm_ouput_get_buffer; timestamp is PCM
 190  * clock time units, not video format time units */
 191 bool pcm_output_commit_data(ssize_t size, uint32_t timestamp)
 192 {
 193     if (size <= 0 || (size & 3))
 194         return false; /* invalid */
 195
 196     size += PCM_HDR_SIZE;
 197
 198     if (size > pcm_output_bytes_free())
 199         return false; /* too big */
 200
 201     pcmbuf_tail->size = size;
 202     pcmbuf_tail->time = timestamp;
 203
 204     pcm_advance_buffer(&pcmbuf_tail, size);
 205     pcmbuf_written += size;
 206
 207     return true;
 208 }
 209
 210 /* Returns 'true' if the buffer is completely empty */
 211 bool pcm_output_empty(void)
 212 {
 213     return pcm_output_bytes_used() <= 0;
 214 }
 215
 216 /* Flushes the buffer - clock keeps counting */
 217 void pcm_output_flush(void)
 218 {
 219     bool playing, paused;
 220
 221     rb->pcm_play_lock();
 222
 223     playing = rb->pcm_is_playing();
 224     paused = rb->pcm_is_paused();
 225
 226     /* Stop PCM to clear current buffer */
 227     if (playing)
 228         rb->pcm_play_stop();
 229
 230     pcm_reset_buffer();
 231
 232     /* Restart if playing state was current */
 233     if (playing && !paused)
 234         rb->pcm_play_data(get_more, NULL, 0);
 235
 236     rb->pcm_play_unlock();
 237 }
 238
 239 /* Seek the reference clock to the specified time - next audio data ready to
 240    go to DMA should be on the buffer with the same time index or else the PCM
 241    buffer should be empty */
 242 void pcm_output_set_clock(uint32_t time)
 243 {
 244     rb->pcm_play_lock();
 245
 246     clock_start = time;
 247     clock_tick = time;
 248     clock_time = time;
 249
 250     rb->pcm_play_unlock();
 251 }
 252
 253 /* Return the clock as synchronized by audio frame timestamps */
 254 uint32_t pcm_output_get_clock(void)
 255 {
 256     uint32_t time, rem;
 257
 258     /* Reread if data race detected - rem will be 0 if driver hasn't yet
 259      * updated to the new buffer size. Also be sure pcm state doesn't
 260      * cause indefinite loop.
 261      *
 262      * FYI: NOT scrutinized for rd/wr reordering on different cores. */
 263     do
 264     {
 265         time = clock_time;
 266         rem = rb->pcm_get_bytes_waiting() >> 2;
 267     }
 268     while (UNLIKELY(time != clock_time ||
 269         (rem == 0 && rb->pcm_is_playing() && !rb->pcm_is_paused())));
 270
 271     return time - rem;
 272
 273 }
 274
 275 /* Return the raw clock as counted from the last pcm_output_set_clock
 276  * call */
 277 uint32_t pcm_output_get_ticks(uint32_t *start)
 278 {
 279     uint32_t tick, rem;
 280
 281     /* Same procedure as pcm_output_get_clock */
 282     do
 283     {
 284         tick = clock_tick;
 285         rem = rb->pcm_get_bytes_waiting() >> 2;
 286     }
 287     while (UNLIKELY(tick != clock_tick ||
 288         (rem == 0 && rb->pcm_is_playing() && !rb->pcm_is_paused())));
 289
 290     if (start)
 291         *start = clock_start;
 292
 293     return tick - rem;
 294 }
 295
 296 /* Pauses/Starts pcm playback - and the clock */
 297 void pcm_output_play_pause(bool play)
 298 {
 299     rb->pcm_play_lock();
 300
 301     if (rb->pcm_is_playing())
 302     {
 303         rb->pcm_play_pause(play);
 304     }
 305     else if (play)
 306     {
 307         rb->pcm_play_data(get_more, NULL, 0);
 308     }
 309
 310     rb->pcm_play_unlock();
 311 }
 312
 313 /* Stops all playback and resets the clock */
 314 void pcm_output_stop(void)
 315 {
 316     rb->pcm_play_lock();
 317
 318     if (rb->pcm_is_playing())
 319         rb->pcm_play_stop();
 320
 321     pcm_output_flush();
 322     pcm_output_set_clock(0);
 323
 324     rb->pcm_play_unlock();
 325 }
 326
 327 /* Drains any data if the start threshold hasn't been reached */
 328 void pcm_output_drain(void)
 329 {
 330     rb->pcm_play_lock();
 331     pcmbuf_threshold = PCMOUT_LOW_WM;
 332     rb->pcm_play_unlock();
 333 }
 334
 335 bool pcm_output_init(void)
 336 {
 337     pcm_buffer = mpeg_malloc(PCMOUT_ALLOC_SIZE, MPEG_ALLOC_PCMOUT);
 338     if (pcm_buffer == NULL)
 339         return false;
 340
 341     pcmbuf_end  = SKIPBYTES(pcm_buffer, PCMOUT_BUFSIZE);
 342
 343     pcm_reset_buffer();
 344
 345     /* Some targets could play at the movie frequency without resampling but
 346      * as of now DSP assumes a certain frequency (always 44100Hz) so
 347      * resampling will be needed for other movie audio rates. */
 348     rb->pcm_set_frequency(NATIVE_FREQUENCY);
 349
 350 #if INPUT_SRC_CAPS != 0
 351     /* Select playback */
 352     rb->audio_set_input_source(AUDIO_SRC_PLAYBACK, SRCF_PLAYBACK);
 353     rb->audio_set_output_source(AUDIO_SRC_PLAYBACK);
 354 #endif
 355
 356 #if SILENCE_TEST_TONE
 357     /* Make the silence clip a square wave */
 358     const int16_t silence_amp = INT16_MAX / 16;
 359     unsigned i;
 360
 361     for (i = 0; i < ARRAYLEN(silence); i += 2)
 362     {
 363         if (i < ARRAYLEN(silence)/2)
 364         {
 365             silence[i] = silence_amp;
 366             silence[i+1] = silence_amp;
 367         }
 368         else
 369         {
 370             silence[i] = -silence_amp;
 371             silence[i+1] = -silence_amp;
 372         }
 373     }
 374 #endif
 375
 376     return true;
 377 }
 378
 379 void pcm_output_exit(void)
 380 {
 381     rb->pcm_set_frequency(HW_SAMPR_DEFAULT);
 382 }