libavcodec/mmaldec.c

   1 /*
   2  * MMAL Video Decoder
   3  * Copyright (c) 2015 Rodger Combs
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * Libav is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * MMAL Video Decoder
  25  */
  26
  27 #include "avcodec.h"
  28 #include "internal.h"
  29 #include "libavutil/atomic.h"
  30 #include "libavutil/avassert.h"
  31 #include "libavutil/buffer.h"
  32 #include "libavutil/common.h"
  33 #include "libavutil/opt.h"
  34 #include "libavutil/log.h"
  35
  36 #include <bcm_host.h>
  37 #include <interface/mmal/mmal.h>
  38 #include <interface/mmal/util/mmal_util.h>
  39 #include <interface/mmal/util/mmal_util_params.h>
  40 #include <interface/mmal/util/mmal_default_components.h>
  41
  42 typedef struct FFBufferEntry {
  43     AVBufferRef *ref;
  44     void *data;
  45     size_t length;
  46     int64_t pts, dts;
  47     int flags;
  48     struct FFBufferEntry *next;
  49 } FFBufferEntry;
  50
  51 // MMAL_POOL_T destroys all of its MMAL_BUFFER_HEADER_Ts. If we want correct
  52 // refcounting for AVFrames, we can free the MMAL_POOL_T only after all AVFrames
  53 // have been unreferenced.
  54 typedef struct FFPoolRef {
  55     volatile int refcount;
  56     MMAL_POOL_T *pool;
  57 } FFPoolRef;
  58
  59 typedef struct FFBufferRef {
  60     MMAL_BUFFER_HEADER_T *buffer;
  61     FFPoolRef *pool;
  62 } FFBufferRef;
  63
  64 typedef struct MMALDecodeContext {
  65     AVClass *av_class;
  66     int extra_buffers;
  67
  68     AVBitStreamFilterContext *bsfc;
  69
  70     MMAL_COMPONENT_T *decoder;
  71     MMAL_QUEUE_T *queue_decoded_frames;
  72     MMAL_POOL_T *pool_in;
  73     FFPoolRef *pool_out;
  74
  75     // Waiting input packets. Because the libavcodec API requires decoding and
  76     // returning packets in lockstep, it can happen that queue_decoded_frames
  77     // contains almost all surfaces - then the decoder input queue can quickly
  78     // fill up and won't accept new input either. Without consuming input, the
  79     // libavcodec API can't return new frames, and we have a logical deadlock.
  80     // This is avoided by queuing such buffers here.
  81     FFBufferEntry *waiting_buffers, *waiting_buffers_tail;
  82
  83     int64_t packets_sent;
  84     int64_t frames_output;
  85     int eos_received;
  86     int eos_sent;
  87 } MMALDecodeContext;
  88
  89 // Assume decoder is guaranteed to produce output after at least this many
  90 // packets (where each packet contains 1 frame).
  91 #define MAX_DELAYED_FRAMES 16
  92
  93 static void ffmmal_poolref_unref(FFPoolRef *ref)
  94 {
  95     if (ref && avpriv_atomic_int_add_and_fetch(&ref->refcount, -1) == 0) {
  96         mmal_pool_destroy(ref->pool);
  97         av_free(ref);
  98     }
  99 }
 100
 101 static void ffmmal_release_frame(void *opaque, uint8_t *data)
 102 {
 103     FFBufferRef *ref = (void *)data;
 104
 105     mmal_buffer_header_release(ref->buffer);
 106     ffmmal_poolref_unref(ref->pool);
 107
 108     av_free(ref);
 109 }
 110
 111 // Setup frame with a new reference to buffer. The buffer must have been
 112 // allocated from the given pool.
 113 static int ffmmal_set_ref(AVFrame *frame, FFPoolRef *pool,
 114                           MMAL_BUFFER_HEADER_T *buffer)
 115 {
 116     FFBufferRef *ref = av_mallocz(sizeof(*ref));
 117     if (!ref)
 118         return AVERROR(ENOMEM);
 119
 120     ref->pool = pool;
 121     ref->buffer = buffer;
 122
 123     frame->buf[0] = av_buffer_create((void *)ref, sizeof(*ref),
 124                                      ffmmal_release_frame, NULL,
 125                                      AV_BUFFER_FLAG_READONLY);
 126     if (!frame->buf[0]) {
 127         av_free(ref);
 128         return AVERROR(ENOMEM);
 129     }
 130
 131     avpriv_atomic_int_add_and_fetch(&ref->pool->refcount, 1);
 132     mmal_buffer_header_acquire(buffer);
 133
 134     frame->format = AV_PIX_FMT_MMAL;
 135     frame->data[3] = (uint8_t *)ref->buffer;
 136     return 0;
 137 }
 138
 139 static void ffmmal_stop_decoder(AVCodecContext *avctx)
 140 {
 141     MMALDecodeContext *ctx = avctx->priv_data;
 142     MMAL_COMPONENT_T *decoder = ctx->decoder;
 143     MMAL_BUFFER_HEADER_T *buffer;
 144
 145     mmal_port_disable(decoder->input[0]);
 146     mmal_port_disable(decoder->output[0]);
 147     mmal_port_disable(decoder->control);
 148
 149     mmal_port_flush(decoder->input[0]);
 150     mmal_port_flush(decoder->output[0]);
 151     mmal_port_flush(decoder->control);
 152
 153     while ((buffer = mmal_queue_get(ctx->queue_decoded_frames)))
 154         mmal_buffer_header_release(buffer);
 155
 156     while (ctx->waiting_buffers) {
 157         FFBufferEntry *buffer = ctx->waiting_buffers;
 158
 159         ctx->waiting_buffers = buffer->next;
 160
 161         av_buffer_unref(&buffer->ref);
 162         av_free(buffer);
 163     }
 164     ctx->waiting_buffers_tail = NULL;
 165
 166     ctx->frames_output = ctx->eos_received = ctx->eos_sent = ctx->packets_sent = 0;
 167 }
 168
 169 static av_cold int ffmmal_close_decoder(AVCodecContext *avctx)
 170 {
 171     MMALDecodeContext *ctx = avctx->priv_data;
 172
 173     if (ctx->decoder)
 174         ffmmal_stop_decoder(avctx);
 175
 176     mmal_component_destroy(ctx->decoder);
 177     ctx->decoder = NULL;
 178     mmal_queue_destroy(ctx->queue_decoded_frames);
 179     mmal_pool_destroy(ctx->pool_in);
 180     ffmmal_poolref_unref(ctx->pool_out);
 181
 182     if (ctx->bsfc)
 183         av_bitstream_filter_close(ctx->bsfc);
 184
 185     return 0;
 186 }
 187
 188 static void input_callback(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
 189 {
 190     if (!buffer->cmd) {
 191         AVBufferRef *buf = buffer->user_data;
 192         av_buffer_unref(&buf);
 193     }
 194     mmal_buffer_header_release(buffer);
 195 }
 196
 197 static void output_callback(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
 198 {
 199     AVCodecContext *avctx = (AVCodecContext*)port->userdata;
 200     MMALDecodeContext *ctx = avctx->priv_data;
 201
 202     mmal_queue_put(ctx->queue_decoded_frames, buffer);
 203 }
 204
 205 static void control_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
 206 {
 207     AVCodecContext *avctx = (AVCodecContext*)port->userdata;
 208     MMAL_STATUS_T status;
 209
 210     if (buffer->cmd == MMAL_EVENT_ERROR) {
 211         status = *(uint32_t *)buffer->data;
 212         av_log(avctx, AV_LOG_ERROR, "MMAL error %d on control port\n", (int)status);
 213     } else {
 214         char s[20];
 215         av_get_codec_tag_string(s, sizeof(s), buffer->cmd);
 216         av_log(avctx, AV_LOG_WARNING, "Unknown MMAL event %s on control port\n", s);
 217     }
 218
 219     mmal_buffer_header_release(buffer);
 220 }
 221
 222 // Feed free output buffers to the decoder.
 223 static int ffmmal_fill_output_port(AVCodecContext *avctx)
 224 {
 225     MMALDecodeContext *ctx = avctx->priv_data;
 226     MMAL_BUFFER_HEADER_T *buffer;
 227     MMAL_STATUS_T status;
 228
 229     if (!ctx->pool_out)
 230         return AVERROR_UNKNOWN; // format change code failed with OOM previously
 231
 232     while ((buffer = mmal_queue_get(ctx->pool_out->pool->queue))) {
 233         if ((status = mmal_port_send_buffer(ctx->decoder->output[0], buffer))) {
 234             mmal_buffer_header_release(buffer);
 235             av_log(avctx, AV_LOG_ERROR, "MMAL error %d when sending output buffer.\n", (int)status);
 236             return AVERROR_UNKNOWN;
 237         }
 238     }
 239
 240     return 0;
 241 }
 242
 243 static enum AVColorSpace ffmmal_csp_to_av_csp(MMAL_FOURCC_T fourcc)
 244 {
 245     switch (fourcc) {
 246     case MMAL_COLOR_SPACE_BT470_2_BG:
 247     case MMAL_COLOR_SPACE_BT470_2_M:
 248     case MMAL_COLOR_SPACE_ITUR_BT601:   return AVCOL_SPC_BT470BG;
 249     case MMAL_COLOR_SPACE_ITUR_BT709:   return AVCOL_SPC_BT709;
 250     case MMAL_COLOR_SPACE_FCC:          return AVCOL_SPC_FCC;
 251     case MMAL_COLOR_SPACE_SMPTE240M:    return AVCOL_SPC_SMPTE240M;
 252     default:                            return AVCOL_SPC_UNSPECIFIED;
 253     }
 254 }
 255
 256 static int ffmal_update_format(AVCodecContext *avctx)
 257 {
 258     MMALDecodeContext *ctx = avctx->priv_data;
 259     MMAL_STATUS_T status;
 260     int ret = 0;
 261     MMAL_COMPONENT_T *decoder = ctx->decoder;
 262     MMAL_ES_FORMAT_T *format_out = decoder->output[0]->format;
 263
 264     ffmmal_poolref_unref(ctx->pool_out);
 265     if (!(ctx->pool_out = av_mallocz(sizeof(*ctx->pool_out)))) {
 266         ret = AVERROR(ENOMEM);
 267         goto fail;
 268     }
 269     ctx->pool_out->refcount = 1;
 270
 271     if (!format_out)
 272         goto fail;
 273
 274     if ((status = mmal_port_parameter_set_uint32(decoder->output[0], MMAL_PARAMETER_EXTRA_BUFFERS, ctx->extra_buffers)))
 275         goto fail;
 276
 277     if (avctx->pix_fmt == AV_PIX_FMT_MMAL) {
 278         format_out->encoding = MMAL_ENCODING_OPAQUE;
 279     } else {
 280         format_out->encoding_variant = format_out->encoding = MMAL_ENCODING_I420;
 281     }
 282
 283     if ((status = mmal_port_format_commit(decoder->output[0])))
 284         goto fail;
 285
 286     if ((ret = ff_set_dimensions(avctx, format_out->es->video.crop.x + format_out->es->video.crop.width,
 287                                         format_out->es->video.crop.y + format_out->es->video.crop.height)) < 0)
 288         goto fail;
 289
 290     if (format_out->es->video.par.num && format_out->es->video.par.den) {
 291         avctx->sample_aspect_ratio.num = format_out->es->video.par.num;
 292         avctx->sample_aspect_ratio.den = format_out->es->video.par.den;
 293     }
 294
 295     avctx->colorspace = ffmmal_csp_to_av_csp(format_out->es->video.color_space);
 296
 297     decoder->output[0]->buffer_size =
 298         FFMAX(decoder->output[0]->buffer_size_min, decoder->output[0]->buffer_size_recommended);
 299     decoder->output[0]->buffer_num =
 300         FFMAX(decoder->output[0]->buffer_num_min, decoder->output[0]->buffer_num_recommended) + ctx->extra_buffers;
 301     ctx->pool_out->pool = mmal_pool_create(decoder->output[0]->buffer_num,
 302                                            decoder->output[0]->buffer_size);
 303     if (!ctx->pool_out->pool) {
 304         ret = AVERROR(ENOMEM);
 305         goto fail;
 306     }
 307
 308     return 0;
 309
 310 fail:
 311     return ret < 0 ? ret : AVERROR_UNKNOWN;
 312 }
 313
 314 static av_cold int ffmmal_init_decoder(AVCodecContext *avctx)
 315 {
 316     MMALDecodeContext *ctx = avctx->priv_data;
 317     MMAL_STATUS_T status;
 318     MMAL_ES_FORMAT_T *format_in;
 319     MMAL_COMPONENT_T *decoder;
 320     int ret = 0;
 321
 322     bcm_host_init();
 323
 324     if ((ret = ff_get_format(avctx, avctx->codec->pix_fmts)) < 0)
 325         return ret;
 326
 327     avctx->pix_fmt = ret;
 328
 329     if ((status = mmal_component_create(MMAL_COMPONENT_DEFAULT_VIDEO_DECODER, &ctx->decoder)))
 330         goto fail;
 331
 332     decoder = ctx->decoder;
 333
 334     format_in = decoder->input[0]->format;
 335     format_in->type = MMAL_ES_TYPE_VIDEO;
 336     format_in->encoding = MMAL_ENCODING_H264;
 337     format_in->es->video.width = FFALIGN(avctx->width, 32);
 338     format_in->es->video.height = FFALIGN(avctx->height, 16);
 339     format_in->es->video.crop.width = avctx->width;
 340     format_in->es->video.crop.height = avctx->height;
 341     format_in->es->video.frame_rate.num = 24000;
 342     format_in->es->video.frame_rate.den = 1001;
 343     format_in->es->video.par.num = avctx->sample_aspect_ratio.num;
 344     format_in->es->video.par.den = avctx->sample_aspect_ratio.den;
 345     format_in->flags = MMAL_ES_FORMAT_FLAG_FRAMED;
 346
 347     if (avctx->codec->id == AV_CODEC_ID_H264 && avctx->extradata && avctx->extradata[0] == 1) {
 348         uint8_t *dummy_p;
 349         int dummy_int;
 350         ctx->bsfc = av_bitstream_filter_init("h264_mp4toannexb");
 351         if (!ctx->bsfc) {
 352             av_log(avctx, AV_LOG_ERROR, "Cannot open the h264_mp4toannexb BSF!\n");
 353             ret = AVERROR(ENOSYS);
 354             goto fail;
 355         }
 356         av_bitstream_filter_filter(ctx->bsfc, avctx, NULL, &dummy_p, &dummy_int, NULL, 0, 0);
 357     }
 358
 359     if (avctx->extradata_size) {
 360         if ((status = mmal_format_extradata_alloc(format_in, avctx->extradata_size)))
 361             goto fail;
 362         format_in->extradata_size = avctx->extradata_size;
 363         memcpy(format_in->extradata, avctx->extradata, format_in->extradata_size);
 364     }
 365
 366     if ((status = mmal_port_format_commit(decoder->input[0])))
 367         goto fail;
 368
 369     decoder->input[0]->buffer_num =
 370         FFMAX(decoder->input[0]->buffer_num_min, 20);
 371     decoder->input[0]->buffer_size =
 372         FFMAX(decoder->input[0]->buffer_size_min, 512 * 1024);
 373     ctx->pool_in = mmal_pool_create(decoder->input[0]->buffer_num, 0);
 374     if (!ctx->pool_in) {
 375         ret = AVERROR(ENOMEM);
 376         goto fail;
 377     }
 378
 379     if ((ret = ffmal_update_format(avctx)) < 0)
 380         goto fail;
 381
 382     ctx->queue_decoded_frames = mmal_queue_create();
 383     if (!ctx->queue_decoded_frames)
 384         goto fail;
 385
 386     decoder->input[0]->userdata = (void*)avctx;
 387     decoder->output[0]->userdata = (void*)avctx;
 388     decoder->control->userdata = (void*)avctx;
 389
 390     if ((status = mmal_port_enable(decoder->control, control_port_cb)))
 391         goto fail;
 392     if ((status = mmal_port_enable(decoder->input[0], input_callback)))
 393         goto fail;
 394     if ((status = mmal_port_enable(decoder->output[0], output_callback)))
 395         goto fail;
 396
 397     if ((status = mmal_component_enable(decoder)))
 398         goto fail;
 399
 400     return 0;
 401
 402 fail:
 403     ffmmal_close_decoder(avctx);
 404     return ret < 0 ? ret : AVERROR_UNKNOWN;
 405 }
 406
 407 static void ffmmal_flush(AVCodecContext *avctx)
 408 {
 409     MMALDecodeContext *ctx = avctx->priv_data;
 410     MMAL_COMPONENT_T *decoder = ctx->decoder;
 411     MMAL_STATUS_T status;
 412
 413     ffmmal_stop_decoder(avctx);
 414
 415     if ((status = mmal_port_enable(decoder->control, control_port_cb)))
 416         goto fail;
 417     if ((status = mmal_port_enable(decoder->input[0], input_callback)))
 418         goto fail;
 419     if ((status = mmal_port_enable(decoder->output[0], output_callback)))
 420         goto fail;
 421
 422     return;
 423
 424 fail:
 425     av_log(avctx, AV_LOG_ERROR, "MMAL flush error: %i\n", (int)status);
 426 }
 427
 428 // Split packets and add them to the waiting_buffers list. We don't queue them
 429 // immediately, because it can happen that the decoder is temporarily blocked
 430 // (due to us not reading/returning enough output buffers) and won't accept
 431 // new input. (This wouldn't be an issue if MMAL input buffers always were
 432 // complete frames - then the input buffer just would have to be big enough.)
 433 static int ffmmal_add_packet(AVCodecContext *avctx, AVPacket *avpkt)
 434 {
 435     MMALDecodeContext *ctx = avctx->priv_data;
 436     AVBufferRef *buf = NULL;
 437     int size = 0;
 438     uint8_t *data = (uint8_t *)"";
 439     uint8_t *start;
 440     int ret = 0;
 441
 442     ctx->packets_sent++;
 443
 444     if (avpkt->size) {
 445         if (ctx->bsfc) {
 446             uint8_t *tmp_data;
 447             int tmp_size;
 448             if ((ret = av_bitstream_filter_filter(ctx->bsfc, avctx, NULL,
 449                                                   &tmp_data, &tmp_size,
 450                                                   avpkt->data, avpkt->size,
 451                                                   avpkt->flags & AV_PKT_FLAG_KEY)) < 0)
 452                 goto done;
 453             buf = av_buffer_create(tmp_data, tmp_size, NULL, NULL, 0);
 454         } else {
 455             if (avpkt->buf) {
 456                 buf = av_buffer_ref(avpkt->buf);
 457             } else {
 458                 buf = av_buffer_alloc(avpkt->size);
 459                 if (buf)
 460                     memcpy(buf->data, avpkt->data, avpkt->size);
 461             }
 462         }
 463         if (!buf) {
 464             ret = AVERROR(ENOMEM);
 465             goto done;
 466         }
 467         size = buf->size;
 468         data = buf->data;
 469     }
 470
 471     start = data;
 472
 473     do {
 474         FFBufferEntry *buffer = av_mallocz(sizeof(*buffer));
 475         if (!buffer) {
 476             ret = AVERROR(ENOMEM);
 477             goto done;
 478         }
 479
 480         buffer->data = data;
 481         buffer->length = FFMIN(size, ctx->decoder->input[0]->buffer_size);
 482
 483         if (data == start)
 484             buffer->flags |= MMAL_BUFFER_HEADER_FLAG_FRAME_START;
 485
 486         data += buffer->length;
 487         size -= buffer->length;
 488
 489         buffer->pts = avpkt->pts == AV_NOPTS_VALUE ? MMAL_TIME_UNKNOWN : avpkt->pts;
 490         buffer->dts = avpkt->dts == AV_NOPTS_VALUE ? MMAL_TIME_UNKNOWN : avpkt->dts;
 491
 492         if (!size)
 493             buffer->flags |= MMAL_BUFFER_HEADER_FLAG_FRAME_END;
 494
 495         if (!buffer->length) {
 496             buffer->flags |= MMAL_BUFFER_HEADER_FLAG_EOS;
 497             ctx->eos_sent = 1;
 498         }
 499
 500         if (buf) {
 501             buffer->ref = av_buffer_ref(buf);
 502             if (!buffer->ref) {
 503                 av_free(buffer);
 504                 ret = AVERROR(ENOMEM);
 505                 goto done;
 506             }
 507         }
 508
 509         // Insert at end of the list
 510         if (!ctx->waiting_buffers)
 511             ctx->waiting_buffers = buffer;
 512         if (ctx->waiting_buffers_tail)
 513             ctx->waiting_buffers_tail->next = buffer;
 514         ctx->waiting_buffers_tail = buffer;
 515     } while (size);
 516
 517 done:
 518     av_buffer_unref(&buf);
 519     return ret;
 520 }
 521
 522 // Move prepared/split packets from waiting_buffers to the MMAL decoder.
 523 static int ffmmal_fill_input_port(AVCodecContext *avctx)
 524 {
 525     MMALDecodeContext *ctx = avctx->priv_data;
 526
 527     while (ctx->waiting_buffers) {
 528         MMAL_BUFFER_HEADER_T *mbuffer;
 529         FFBufferEntry *buffer;
 530         MMAL_STATUS_T status;
 531
 532         mbuffer = mmal_queue_get(ctx->pool_in->queue);
 533         if (!mbuffer)
 534             return 0;
 535
 536         buffer = ctx->waiting_buffers;
 537
 538         mmal_buffer_header_reset(mbuffer);
 539         mbuffer->cmd = 0;
 540         mbuffer->pts = buffer->pts;
 541         mbuffer->dts = buffer->dts;
 542         mbuffer->flags = buffer->flags;
 543         mbuffer->data = buffer->data;
 544         mbuffer->length = buffer->length;
 545         mbuffer->user_data = buffer->ref;
 546         mbuffer->alloc_size = ctx->decoder->input[0]->buffer_size;
 547
 548         if ((status = mmal_port_send_buffer(ctx->decoder->input[0], mbuffer))) {
 549             mmal_buffer_header_release(mbuffer);
 550             av_buffer_unref(&buffer->ref);
 551         }
 552
 553         // Remove from start of the list
 554         ctx->waiting_buffers = buffer->next;
 555         if (ctx->waiting_buffers_tail == buffer)
 556             ctx->waiting_buffers_tail = NULL;
 557         av_free(buffer);
 558
 559         if (status) {
 560             av_log(avctx, AV_LOG_ERROR, "MMAL error %d when sending input\n", (int)status);
 561             return AVERROR_UNKNOWN;
 562         }
 563     }
 564
 565     return 0;
 566 }
 567
 568 static int ffmal_copy_frame(AVCodecContext *avctx,  AVFrame *frame,
 569                             MMAL_BUFFER_HEADER_T *buffer)
 570 {
 571     MMALDecodeContext *ctx = avctx->priv_data;
 572     int ret = 0;
 573
 574     if (avctx->pix_fmt == AV_PIX_FMT_MMAL) {
 575         if (!ctx->pool_out)
 576             return AVERROR_UNKNOWN; // format change code failed with OOM previously
 577
 578         if ((ret = ff_decode_frame_props(avctx, frame)) < 0)
 579             goto done;
 580
 581         if ((ret = ffmmal_set_ref(frame, ctx->pool_out, buffer)) < 0)
 582             goto done;
 583     } else {
 584         int w = FFALIGN(avctx->width, 32);
 585         int h = FFALIGN(avctx->height, 16);
 586         char *ptr;
 587         int plane;
 588         int i;
 589
 590         if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
 591             goto done;
 592
 593         ptr = buffer->data + buffer->type->video.offset[0];
 594         for (i = 0; i < avctx->height; i++)
 595             memcpy(frame->data[0] + frame->linesize[0] * i, ptr + w * i, avctx->width);
 596
 597         ptr += w * h;
 598
 599         for (plane = 1; plane < 3; plane++) {
 600             for (i = 0; i < avctx->height / 2; i++)
 601                 memcpy(frame->data[plane] + frame->linesize[plane] * i, ptr + w / 2 * i, (avctx->width + 1) / 2);
 602             ptr += w / 2 * h / 2;
 603         }
 604     }
 605
 606     if (buffer->pts != MMAL_TIME_UNKNOWN) {
 607         frame->pkt_pts = buffer->pts;
 608         frame->pts = buffer->pts;
 609     }
 610
 611 done:
 612     return ret;
 613 }
 614
 615 // Fetch a decoded buffer and place it into the frame parameter.
 616 static int ffmmal_read_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame)
 617 {
 618     MMALDecodeContext *ctx = avctx->priv_data;
 619     MMAL_BUFFER_HEADER_T *buffer = NULL;
 620     MMAL_STATUS_T status = 0;
 621     int ret = 0;
 622
 623     if (ctx->eos_received)
 624         goto done;
 625
 626     while (1) {
 627         // To ensure decoding in lockstep with a constant delay between fed packets
 628         // and output frames, we always wait until an output buffer is available.
 629         // Except during start we don't know after how many input packets the decoder
 630         // is going to return the first buffer, and we can't distinguish decoder
 631         // being busy from decoder waiting for input. So just poll at the start and
 632         // keep feeding new data to the buffer.
 633         // We are pretty sure the decoder will produce output if we sent more input
 634         // frames than what a h264 decoder could logically delay. This avoids too
 635         // excessive buffering.
 636         // We also wait if we sent eos, but didn't receive it yet (think of decoding
 637         // stream with a very low number of frames).
 638         if (ctx->frames_output || ctx->packets_sent > MAX_DELAYED_FRAMES || ctx->eos_sent) {
 639             buffer = mmal_queue_wait(ctx->queue_decoded_frames);
 640         } else {
 641             buffer = mmal_queue_get(ctx->queue_decoded_frames);
 642         }
 643         if (!buffer)
 644             goto done;
 645
 646         ctx->eos_received |= !!(buffer->flags & MMAL_BUFFER_HEADER_FLAG_EOS);
 647         if (ctx->eos_received)
 648             goto done;
 649
 650         if (buffer->cmd == MMAL_EVENT_FORMAT_CHANGED) {
 651             MMAL_COMPONENT_T *decoder = ctx->decoder;
 652             MMAL_EVENT_FORMAT_CHANGED_T *ev = mmal_event_format_changed_get(buffer);
 653             MMAL_BUFFER_HEADER_T *stale_buffer;
 654
 655             av_log(avctx, AV_LOG_INFO, "Changing output format.\n");
 656
 657             if ((status = mmal_port_disable(decoder->output[0])))
 658                 goto done;
 659
 660             while ((stale_buffer = mmal_queue_get(ctx->queue_decoded_frames)))
 661                 mmal_buffer_header_release(stale_buffer);
 662
 663             mmal_format_copy(decoder->output[0]->format, ev->format);
 664
 665             if ((ret = ffmal_update_format(avctx)) < 0)
 666                 goto done;
 667
 668             if ((status = mmal_port_enable(decoder->output[0], output_callback)))
 669                 goto done;
 670
 671             if ((ret = ffmmal_fill_output_port(avctx)) < 0)
 672                 goto done;
 673
 674             if ((ret = ffmmal_fill_input_port(avctx)) < 0)
 675                 goto done;
 676
 677             mmal_buffer_header_release(buffer);
 678             continue;
 679         } else if (buffer->cmd) {
 680             char s[20];
 681             av_get_codec_tag_string(s, sizeof(s), buffer->cmd);
 682             av_log(avctx, AV_LOG_WARNING, "Unknown MMAL event %s on output port\n", s);
 683             goto done;
 684         } else if (buffer->length == 0) {
 685             // Unused output buffer that got drained after format change.
 686             mmal_buffer_header_release(buffer);
 687             continue;
 688         }
 689
 690         ctx->frames_output++;
 691
 692         if ((ret = ffmal_copy_frame(avctx, frame, buffer)) < 0)
 693             goto done;
 694
 695         *got_frame = 1;
 696         break;
 697     }
 698
 699 done:
 700     if (buffer)
 701         mmal_buffer_header_release(buffer);
 702     if (status && ret >= 0)
 703         ret = AVERROR_UNKNOWN;
 704     return ret;
 705 }
 706
 707 static int ffmmal_decode(AVCodecContext *avctx, void *data, int *got_frame,
 708                          AVPacket *avpkt)
 709 {
 710     AVFrame *frame = data;
 711     int ret = 0;
 712
 713     if ((ret = ffmmal_add_packet(avctx, avpkt)) < 0)
 714         return ret;
 715
 716     if ((ret = ffmmal_fill_input_port(avctx)) < 0)
 717         return ret;
 718
 719     if ((ret = ffmmal_fill_output_port(avctx)) < 0)
 720         return ret;
 721
 722     if ((ret = ffmmal_read_frame(avctx, frame, got_frame)) < 0)
 723         return ret;
 724
 725     // ffmmal_read_frame() can block for a while. Since the decoder is
 726     // asynchronous, it's a good idea to fill the ports again.
 727
 728     if ((ret = ffmmal_fill_output_port(avctx)) < 0)
 729         return ret;
 730
 731     if ((ret = ffmmal_fill_input_port(avctx)) < 0)
 732         return ret;
 733
 734     return ret;
 735 }
 736
 737 AVHWAccel ff_h264_mmal_hwaccel = {
 738     .name       = "h264_mmal",
 739     .type       = AVMEDIA_TYPE_VIDEO,
 740     .id         = AV_CODEC_ID_H264,
 741     .pix_fmt    = AV_PIX_FMT_MMAL,
 742 };
 743
 744 static const AVOption options[]={
 745     {"extra_buffers", "extra buffers", offsetof(MMALDecodeContext, extra_buffers), AV_OPT_TYPE_INT, {.i64 = 10}, 0, 256, 0},
 746     {NULL}
 747 };
 748
 749 static const AVClass ffmmaldec_class = {
 750     .class_name = "mmaldec",
 751     .option     = options,
 752     .version    = LIBAVUTIL_VERSION_INT,
 753 };
 754
 755 AVCodec ff_h264_mmal_decoder = {
 756     .name           = "h264_mmal",
 757     .long_name      = NULL_IF_CONFIG_SMALL("h264 (mmal)"),
 758     .type           = AVMEDIA_TYPE_VIDEO,
 759     .id             = AV_CODEC_ID_H264,
 760     .priv_data_size = sizeof(MMALDecodeContext),
 761     .init           = ffmmal_init_decoder,
 762     .close          = ffmmal_close_decoder,
 763     .decode         = ffmmal_decode,
 764     .flush          = ffmmal_flush,
 765     .priv_class     = &ffmmaldec_class,
 766     .capabilities   = CODEC_CAP_DELAY,
 767     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_MMAL,
 768                                                      AV_PIX_FMT_YUV420P,
 769                                                      AV_PIX_FMT_NONE},
 770 };