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  1. /*
  2.  * MMAL Video Decoder
  3.  * Copyright (c) 2015 Rodger Combs
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg 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.  * FFmpeg 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 FFmpeg; 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 <bcm_host.h>
  28. #include <interface/mmal/mmal.h>
  29. #include <interface/mmal/util/mmal_util.h>
  30. #include <interface/mmal/util/mmal_util_params.h>
  31. #include <interface/mmal/util/mmal_default_components.h>
  32. #include <interface/mmal/vc/mmal_vc_api.h>
  33.  
  34. #include "avcodec.h"
  35. #include "internal.h"
  36. #include "libavutil/atomic.h"
  37. #include "libavutil/avassert.h"
  38. #include "libavutil/buffer.h"
  39. #include "libavutil/common.h"
  40. #include "libavutil/opt.h"
  41. #include "libavutil/log.h"
  42.  
  43. typedef struct FFBufferEntry {
  44.     AVBufferRef *ref;
  45.     void *data;
  46.     size_t length;
  47.     int64_t pts, dts;
  48.     int flags;
  49.     struct FFBufferEntry *next;
  50. } FFBufferEntry;
  51.  
  52. // MMAL_POOL_T destroys all of its MMAL_BUFFER_HEADER_Ts. If we want correct
  53. // refcounting for AVFrames, we can free the MMAL_POOL_T only after all AVFrames
  54. // have been unreferenced.
  55. typedef struct FFPoolRef {
  56.     volatile int refcount;
  57.     MMAL_POOL_T *pool;
  58. } FFPoolRef;
  59.  
  60. typedef struct FFBufferRef {
  61.     MMAL_BUFFER_HEADER_T *buffer;
  62.     FFPoolRef *pool;
  63. } FFBufferRef;
  64.  
  65. typedef struct MMALDecodeContext {
  66.     AVClass *av_class;
  67.     int extra_buffers;
  68.  
  69.     AVBitStreamFilterContext *bsfc;
  70.  
  71.     MMAL_COMPONENT_T *decoder;
  72.     MMAL_QUEUE_T *queue_decoded_frames;
  73.     MMAL_POOL_T *pool_in;
  74.     FFPoolRef *pool_out;
  75.  
  76.     // Waiting input packets. Because the libavcodec API requires decoding and
  77.     // returning packets in lockstep, it can happen that queue_decoded_frames
  78.     // contains almost all surfaces - then the decoder input queue can quickly
  79.     // fill up and won't accept new input either. Without consuming input, the
  80.     // libavcodec API can't return new frames, and we have a logical deadlock.
  81.     // This is avoided by queuing such buffers here.
  82.     FFBufferEntry *waiting_buffers, *waiting_buffers_tail;
  83.  
  84.     int64_t packets_sent;
  85.     int64_t frames_output;
  86.     int eos_received;
  87.     int eos_sent;
  88. } MMALDecodeContext;
  89.  
  90. // Assume decoder is guaranteed to produce output after at least this many
  91. // packets (where each packet contains 1 frame).
  92. #define MAX_DELAYED_FRAMES 16
  93.  
  94. static void ffmmal_poolref_unref(FFPoolRef *ref)
  95. {
  96.     if (ref && avpriv_atomic_int_add_and_fetch(&ref->refcount, -1) == 0) {
  97.         mmal_pool_destroy(ref->pool);
  98.         av_free(ref);
  99.     }
  100. }
  101.  
  102. static void ffmmal_release_frame(void *opaque, uint8_t *data)
  103. {
  104.     FFBufferRef *ref = (void *)data;
  105.  
  106.     mmal_buffer_header_release(ref->buffer);
  107.     ffmmal_poolref_unref(ref->pool);
  108.  
  109.     av_free(ref);
  110. }
  111.  
  112. // Setup frame with a new reference to buffer. The buffer must have been
  113. // allocated from the given pool.
  114. static int ffmmal_set_ref(AVFrame *frame, FFPoolRef *pool,
  115.                           MMAL_BUFFER_HEADER_T *buffer)
  116. {
  117.     FFBufferRef *ref = av_mallocz(sizeof(*ref));
  118.     if (!ref)
  119.         return AVERROR(ENOMEM);
  120.  
  121.     ref->pool = pool;
  122.     ref->buffer = buffer;
  123.  
  124.     frame->buf[0] = av_buffer_create((void *)ref, sizeof(*ref),
  125.                                      ffmmal_release_frame, NULL,
  126.                                      AV_BUFFER_FLAG_READONLY);
  127.     if (!frame->buf[0]) {
  128.         av_free(ref);
  129.         return AVERROR(ENOMEM);
  130.     }
  131.  
  132.     avpriv_atomic_int_add_and_fetch(&ref->pool->refcount, 1);
  133.     mmal_buffer_header_acquire(buffer);
  134.  
  135.     frame->format = AV_PIX_FMT_MMAL;
  136.     frame->data[3] = (uint8_t *)ref->buffer;
  137.     return 0;
  138. }
  139.  
  140. static void ffmmal_stop_decoder(AVCodecContext *avctx)
  141. {
  142.     MMALDecodeContext *ctx = avctx->priv_data;
  143.     MMAL_COMPONENT_T *decoder = ctx->decoder;
  144.     MMAL_BUFFER_HEADER_T *buffer;
  145.  
  146.     mmal_port_disable(decoder->input[0]);
  147.     mmal_port_disable(decoder->output[0]);
  148.     mmal_port_disable(decoder->control);
  149.  
  150.     mmal_port_flush(decoder->input[0]);
  151.     mmal_port_flush(decoder->output[0]);
  152.     mmal_port_flush(decoder->control);
  153.  
  154.     while ((buffer = mmal_queue_get(ctx->queue_decoded_frames)))
  155.         mmal_buffer_header_release(buffer);
  156.  
  157.     while (ctx->waiting_buffers) {
  158.         FFBufferEntry *buffer = ctx->waiting_buffers;
  159.  
  160.         ctx->waiting_buffers = buffer->next;
  161.  
  162.         av_buffer_unref(&buffer->ref);
  163.         av_free(buffer);
  164.     }
  165.     ctx->waiting_buffers_tail = NULL;
  166.  
  167.     ctx->frames_output = ctx->eos_received = ctx->eos_sent = ctx->packets_sent = 0;
  168. }
  169.  
  170. static av_cold int ffmmal_close_decoder(AVCodecContext *avctx)
  171. {
  172.     MMALDecodeContext *ctx = avctx->priv_data;
  173.  
  174.     if (ctx->decoder)
  175.         ffmmal_stop_decoder(avctx);
  176.  
  177.     mmal_component_destroy(ctx->decoder);
  178.     ctx->decoder = NULL;
  179.     mmal_queue_destroy(ctx->queue_decoded_frames);
  180.     mmal_pool_destroy(ctx->pool_in);
  181.     ffmmal_poolref_unref(ctx->pool_out);
  182.  
  183.     if (ctx->bsfc)
  184.         av_bitstream_filter_close(ctx->bsfc);
  185.  
  186.     mmal_vc_deinit();
  187.  
  188.     return 0;
  189. }
  190.  
  191. static void input_callback(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
  192. {
  193.     if (!buffer->cmd) {
  194.         AVBufferRef *buf = buffer->user_data;
  195.         av_buffer_unref(&buf);
  196.     }
  197.     mmal_buffer_header_release(buffer);
  198. }
  199.  
  200. static void output_callback(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
  201. {
  202.     AVCodecContext *avctx = (AVCodecContext*)port->userdata;
  203.     MMALDecodeContext *ctx = avctx->priv_data;
  204.  
  205.     mmal_queue_put(ctx->queue_decoded_frames, buffer);
  206. }
  207.  
  208. static void control_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
  209. {
  210.     AVCodecContext *avctx = (AVCodecContext*)port->userdata;
  211.     MMAL_STATUS_T status;
  212.  
  213.     if (buffer->cmd == MMAL_EVENT_ERROR) {
  214.         status = *(uint32_t *)buffer->data;
  215.         av_log(avctx, AV_LOG_ERROR, "MMAL error %d on control port\n", (int)status);
  216.     } else {
  217.         char s[20];
  218.         av_get_codec_tag_string(s, sizeof(s), buffer->cmd);
  219.         av_log(avctx, AV_LOG_WARNING, "Unknown MMAL event %s on control port\n", s);
  220.     }
  221.  
  222.     mmal_buffer_header_release(buffer);
  223. }
  224.  
  225. // Feed free output buffers to the decoder.
  226. static int ffmmal_fill_output_port(AVCodecContext *avctx)
  227. {
  228.     MMALDecodeContext *ctx = avctx->priv_data;
  229.     MMAL_BUFFER_HEADER_T *buffer;
  230.     MMAL_STATUS_T status;
  231.  
  232.     if (!ctx->pool_out)
  233.         return AVERROR_UNKNOWN; // format change code failed with OOM previously
  234.  
  235.     while ((buffer = mmal_queue_get(ctx->pool_out->pool->queue))) {
  236.         if ((status = mmal_port_send_buffer(ctx->decoder->output[0], buffer))) {
  237.             mmal_buffer_header_release(buffer);
  238.             av_log(avctx, AV_LOG_ERROR, "MMAL error %d when sending output buffer.\n", (int)status);
  239.             return AVERROR_UNKNOWN;
  240.         }
  241.     }
  242.  
  243.     return 0;
  244. }
  245.  
  246. static enum AVColorSpace ffmmal_csp_to_av_csp(MMAL_FOURCC_T fourcc)
  247. {
  248.     switch (fourcc) {
  249.     case MMAL_COLOR_SPACE_BT470_2_BG:
  250.     case MMAL_COLOR_SPACE_BT470_2_M:
  251.     case MMAL_COLOR_SPACE_ITUR_BT601:   return AVCOL_SPC_BT470BG;
  252.     case MMAL_COLOR_SPACE_ITUR_BT709:   return AVCOL_SPC_BT709;
  253.     case MMAL_COLOR_SPACE_FCC:          return AVCOL_SPC_FCC;
  254.     case MMAL_COLOR_SPACE_SMPTE240M:    return AVCOL_SPC_SMPTE240M;
  255.     default:                            return AVCOL_SPC_UNSPECIFIED;
  256.     }
  257. }
  258.  
  259. static int ffmal_update_format(AVCodecContext *avctx)
  260. {
  261.     MMALDecodeContext *ctx = avctx->priv_data;
  262.     MMAL_STATUS_T status;
  263.     int ret = 0;
  264.     MMAL_COMPONENT_T *decoder = ctx->decoder;
  265.     MMAL_ES_FORMAT_T *format_out = decoder->output[0]->format;
  266.  
  267.     ffmmal_poolref_unref(ctx->pool_out);
  268.     if (!(ctx->pool_out = av_mallocz(sizeof(*ctx->pool_out)))) {
  269.         ret = AVERROR(ENOMEM);
  270.         goto fail;
  271.     }
  272.     ctx->pool_out->refcount = 1;
  273.  
  274.     if (!format_out)
  275.         goto fail;
  276.  
  277.     if ((status = mmal_port_parameter_set_uint32(decoder->output[0], MMAL_PARAMETER_EXTRA_BUFFERS, ctx->extra_buffers)))
  278.         goto fail;
  279.  
  280.     if (avctx->pix_fmt == AV_PIX_FMT_MMAL) {
  281.         format_out->encoding = MMAL_ENCODING_OPAQUE;
  282.     } else {
  283.         format_out->encoding_variant = format_out->encoding = MMAL_ENCODING_I420;
  284.     }
  285.  
  286.     if ((status = mmal_port_format_commit(decoder->output[0])))
  287.         goto fail;
  288.  
  289.     if ((ret = ff_set_dimensions(avctx, format_out->es->video.crop.x + format_out->es->video.crop.width,
  290.                                         format_out->es->video.crop.y + format_out->es->video.crop.height)) < 0)
  291.         goto fail;
  292.  
  293.     if (format_out->es->video.par.num && format_out->es->video.par.den) {
  294.         avctx->sample_aspect_ratio.num = format_out->es->video.par.num;
  295.         avctx->sample_aspect_ratio.den = format_out->es->video.par.den;
  296.     }
  297.  
  298.     avctx->colorspace = ffmmal_csp_to_av_csp(format_out->es->video.color_space);
  299.  
  300.     decoder->output[0]->buffer_size =
  301.         FFMAX(decoder->output[0]->buffer_size_min, decoder->output[0]->buffer_size_recommended);
  302.     decoder->output[0]->buffer_num =
  303.         FFMAX(decoder->output[0]->buffer_num_min, decoder->output[0]->buffer_num_recommended) + ctx->extra_buffers;
  304.     ctx->pool_out->pool = mmal_pool_create(decoder->output[0]->buffer_num,
  305.                                            decoder->output[0]->buffer_size);
  306.     if (!ctx->pool_out->pool) {
  307.         ret = AVERROR(ENOMEM);
  308.         goto fail;
  309.     }
  310.  
  311.     return 0;
  312.  
  313. fail:
  314.     return ret < 0 ? ret : AVERROR_UNKNOWN;
  315. }
  316.  
  317. static av_cold int ffmmal_init_decoder(AVCodecContext *avctx)
  318. {
  319.     MMALDecodeContext *ctx = avctx->priv_data;
  320.     MMAL_STATUS_T status;
  321.     MMAL_ES_FORMAT_T *format_in;
  322.     MMAL_COMPONENT_T *decoder;
  323.     int ret = 0;
  324.  
  325.     bcm_host_init();
  326.  
  327.     if (mmal_vc_init()) {
  328.         av_log(avctx, AV_LOG_ERROR, "Cannot initialize MMAL VC driver!\n");
  329.         return AVERROR(ENOSYS);
  330.     }
  331.  
  332.     if ((ret = ff_get_format(avctx, avctx->codec->pix_fmts)) < 0)
  333.         return ret;
  334.  
  335.     avctx->pix_fmt = ret;
  336.  
  337.     if ((status = mmal_component_create(MMAL_COMPONENT_DEFAULT_VIDEO_DECODER, &ctx->decoder)))
  338.         goto fail;
  339.  
  340.     decoder = ctx->decoder;
  341.  
  342.     format_in = decoder->input[0]->format;
  343.     format_in->type = MMAL_ES_TYPE_VIDEO;
  344.     format_in->encoding = MMAL_ENCODING_H264;
  345.     format_in->es->video.width = FFALIGN(avctx->width, 32);
  346.     format_in->es->video.height = FFALIGN(avctx->height, 16);
  347.     format_in->es->video.crop.width = avctx->width;
  348.     format_in->es->video.crop.height = avctx->height;
  349.     format_in->es->video.frame_rate.num = 24000;
  350.     format_in->es->video.frame_rate.den = 1001;
  351.     format_in->es->video.par.num = avctx->sample_aspect_ratio.num;
  352.     format_in->es->video.par.den = avctx->sample_aspect_ratio.den;
  353.     format_in->flags = MMAL_ES_FORMAT_FLAG_FRAMED;
  354.  
  355.     if (avctx->codec->id == AV_CODEC_ID_H264 && avctx->extradata && avctx->extradata[0] == 1) {
  356.         uint8_t *dummy_p;
  357.         int dummy_int;
  358.         ctx->bsfc = av_bitstream_filter_init("h264_mp4toannexb");
  359.         if (!ctx->bsfc) {
  360.             av_log(avctx, AV_LOG_ERROR, "Cannot open the h264_mp4toannexb BSF!\n");
  361.             ret = AVERROR(ENOSYS);
  362.             goto fail;
  363.         }
  364.         av_bitstream_filter_filter(ctx->bsfc, avctx, "private_spspps_buf", &dummy_p, &dummy_int, NULL, 0, 0);
  365.     } else if (avctx->extradata_size) {
  366.         if ((status = mmal_format_extradata_alloc(format_in, avctx->extradata_size)))
  367.             goto fail;
  368.         format_in->extradata_size = avctx->extradata_size;
  369.         memcpy(format_in->extradata, avctx->extradata, format_in->extradata_size);
  370.     }
  371.  
  372.     if ((status = mmal_port_format_commit(decoder->input[0])))
  373.         goto fail;
  374.  
  375.     decoder->input[0]->buffer_num =
  376.         FFMAX(decoder->input[0]->buffer_num_min, 20);
  377.     decoder->input[0]->buffer_size =
  378.         FFMAX(decoder->input[0]->buffer_size_min, 512 * 1024);
  379.     ctx->pool_in = mmal_pool_create(decoder->input[0]->buffer_num, 0);
  380.     if (!ctx->pool_in) {
  381.         ret = AVERROR(ENOMEM);
  382.         goto fail;
  383.     }
  384.  
  385.     if ((ret = ffmal_update_format(avctx)) < 0)
  386.         goto fail;
  387.  
  388.     ctx->queue_decoded_frames = mmal_queue_create();
  389.     if (!ctx->queue_decoded_frames)
  390.         goto fail;
  391.  
  392.     decoder->input[0]->userdata = (void*)avctx;
  393.     decoder->output[0]->userdata = (void*)avctx;
  394.     decoder->control->userdata = (void*)avctx;
  395.  
  396.     if ((status = mmal_port_enable(decoder->control, control_port_cb)))
  397.         goto fail;
  398.     if ((status = mmal_port_enable(decoder->input[0], input_callback)))
  399.         goto fail;
  400.     if ((status = mmal_port_enable(decoder->output[0], output_callback)))
  401.         goto fail;
  402.  
  403.     if ((status = mmal_component_enable(decoder)))
  404.         goto fail;
  405.  
  406.     return 0;
  407.  
  408. fail:
  409.     ffmmal_close_decoder(avctx);
  410.     return ret < 0 ? ret : AVERROR_UNKNOWN;
  411. }
  412.  
  413. static void ffmmal_flush(AVCodecContext *avctx)
  414. {
  415.     MMALDecodeContext *ctx = avctx->priv_data;
  416.     MMAL_COMPONENT_T *decoder = ctx->decoder;
  417.     MMAL_STATUS_T status;
  418.  
  419.     ffmmal_stop_decoder(avctx);
  420.  
  421.     if ((status = mmal_port_enable(decoder->control, control_port_cb)))
  422.         goto fail;
  423.     if ((status = mmal_port_enable(decoder->input[0], input_callback)))
  424.         goto fail;
  425.     if ((status = mmal_port_enable(decoder->output[0], output_callback)))
  426.         goto fail;
  427.  
  428.     return;
  429.  
  430. fail:
  431.     av_log(avctx, AV_LOG_ERROR, "MMAL flush error: %i\n", (int)status);
  432. }
  433.  
  434. // Split packets and add them to the waiting_buffers list. We don't queue them
  435. // immediately, because it can happen that the decoder is temporarily blocked
  436. // (due to us not reading/returning enough output buffers) and won't accept
  437. // new input. (This wouldn't be an issue if MMAL input buffers always were
  438. // complete frames - then the input buffer just would have to be big enough.)
  439. static int ffmmal_add_packet(AVCodecContext *avctx, AVPacket *avpkt)
  440. {
  441.     MMALDecodeContext *ctx = avctx->priv_data;
  442.     AVBufferRef *buf = NULL;
  443.     int size = 0;
  444.     uint8_t *data = (uint8_t *)"";
  445.     uint8_t *start;
  446.     int ret = 0;
  447.  
  448.     if (avpkt->size) {
  449.         if (ctx->bsfc) {
  450.             uint8_t *tmp_data;
  451.             int tmp_size;
  452.             if ((ret = av_bitstream_filter_filter(ctx->bsfc, avctx, "private_spspps_buf",
  453.                                                   &tmp_data, &tmp_size,
  454.                                                   avpkt->data, avpkt->size,
  455.                                                   avpkt->flags & AV_PKT_FLAG_KEY)) < 0)
  456.                 goto done;
  457.             buf = av_buffer_create(tmp_data, tmp_size, NULL, NULL, 0);
  458.         } else {
  459.             if (avpkt->buf) {
  460.                 buf = av_buffer_ref(avpkt->buf);
  461.             } else {
  462.                 buf = av_buffer_alloc(avpkt->size);
  463.                 if (buf)
  464.                     memcpy(buf->data, avpkt->data, avpkt->size);
  465.             }
  466.         }
  467.         if (!buf) {
  468.             ret = AVERROR(ENOMEM);
  469.             goto done;
  470.         }
  471.         size = buf->size;
  472.         data = buf->data;
  473.         ctx->packets_sent++;
  474.     } else {
  475.         if (!ctx->packets_sent) {
  476.             // Short-cut the flush logic to avoid upsetting MMAL.
  477.             ctx->eos_sent = 1;
  478.             ctx->eos_received = 1;
  479.             goto done;
  480.         }
  481.     }
  482.  
  483.     start = data;
  484.  
  485.     do {
  486.         FFBufferEntry *buffer = av_mallocz(sizeof(*buffer));
  487.         if (!buffer) {
  488.             ret = AVERROR(ENOMEM);
  489.             goto done;
  490.         }
  491.  
  492.         buffer->data = data;
  493.         buffer->length = FFMIN(size, ctx->decoder->input[0]->buffer_size);
  494.  
  495.         if (data == start)
  496.             buffer->flags |= MMAL_BUFFER_HEADER_FLAG_FRAME_START;
  497.  
  498.         data += buffer->length;
  499.         size -= buffer->length;
  500.  
  501.         buffer->pts = avpkt->pts == AV_NOPTS_VALUE ? MMAL_TIME_UNKNOWN : avpkt->pts;
  502.         buffer->dts = avpkt->dts == AV_NOPTS_VALUE ? MMAL_TIME_UNKNOWN : avpkt->dts;
  503.  
  504.         if (!size)
  505.             buffer->flags |= MMAL_BUFFER_HEADER_FLAG_FRAME_END;
  506.  
  507.         if (!buffer->length) {
  508.             buffer->flags |= MMAL_BUFFER_HEADER_FLAG_EOS;
  509.             ctx->eos_sent = 1;
  510.         }
  511.  
  512.         if (buf) {
  513.             buffer->ref = av_buffer_ref(buf);
  514.             if (!buffer->ref) {
  515.                 av_free(buffer);
  516.                 ret = AVERROR(ENOMEM);
  517.                 goto done;
  518.             }
  519.         }
  520.  
  521.         // Insert at end of the list
  522.         if (!ctx->waiting_buffers)
  523.             ctx->waiting_buffers = buffer;
  524.         if (ctx->waiting_buffers_tail)
  525.             ctx->waiting_buffers_tail->next = buffer;
  526.         ctx->waiting_buffers_tail = buffer;
  527.     } while (size);
  528.  
  529. done:
  530.     av_buffer_unref(&buf);
  531.     return ret;
  532. }
  533.  
  534. // Move prepared/split packets from waiting_buffers to the MMAL decoder.
  535. static int ffmmal_fill_input_port(AVCodecContext *avctx)
  536. {
  537.     MMALDecodeContext *ctx = avctx->priv_data;
  538.  
  539.     while (ctx->waiting_buffers) {
  540.         MMAL_BUFFER_HEADER_T *mbuffer;
  541.         FFBufferEntry *buffer;
  542.         MMAL_STATUS_T status;
  543.  
  544.         mbuffer = mmal_queue_get(ctx->pool_in->queue);
  545.         if (!mbuffer)
  546.             return 0;
  547.  
  548.         buffer = ctx->waiting_buffers;
  549.  
  550.         mmal_buffer_header_reset(mbuffer);
  551.         mbuffer->cmd = 0;
  552.         mbuffer->pts = buffer->pts;
  553.         mbuffer->dts = buffer->dts;
  554.         mbuffer->flags = buffer->flags;
  555.         mbuffer->data = buffer->data;
  556.         mbuffer->length = buffer->length;
  557.         mbuffer->user_data = buffer->ref;
  558.         mbuffer->alloc_size = ctx->decoder->input[0]->buffer_size;
  559.  
  560.         if ((status = mmal_port_send_buffer(ctx->decoder->input[0], mbuffer))) {
  561.             mmal_buffer_header_release(mbuffer);
  562.             av_buffer_unref(&buffer->ref);
  563.         }
  564.  
  565.         // Remove from start of the list
  566.         ctx->waiting_buffers = buffer->next;
  567.         if (ctx->waiting_buffers_tail == buffer)
  568.             ctx->waiting_buffers_tail = NULL;
  569.         av_free(buffer);
  570.  
  571.         if (status) {
  572.             av_log(avctx, AV_LOG_ERROR, "MMAL error %d when sending input\n", (int)status);
  573.             return AVERROR_UNKNOWN;
  574.         }
  575.     }
  576.  
  577.     return 0;
  578. }
  579.  
  580. static int ffmal_copy_frame(AVCodecContext *avctx,  AVFrame *frame,
  581.                             MMAL_BUFFER_HEADER_T *buffer)
  582. {
  583.     MMALDecodeContext *ctx = avctx->priv_data;
  584.     int ret = 0;
  585.  
  586.     if (avctx->pix_fmt == AV_PIX_FMT_MMAL) {
  587.         if (!ctx->pool_out)
  588.             return AVERROR_UNKNOWN; // format change code failed with OOM previously
  589.  
  590.         if ((ret = ff_decode_frame_props(avctx, frame)) < 0)
  591.             goto done;
  592.  
  593.         if ((ret = ffmmal_set_ref(frame, ctx->pool_out, buffer)) < 0)
  594.             goto done;
  595.     } else {
  596.         int w = FFALIGN(avctx->width, 32);
  597.         int h = FFALIGN(avctx->height, 16);
  598.         char *ptr;
  599.         int plane;
  600.         int i;
  601.  
  602.         if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  603.             goto done;
  604.  
  605.         ptr = buffer->data + buffer->type->video.offset[0];
  606.         for (i = 0; i < avctx->height; i++)
  607.             memcpy(frame->data[0] + frame->linesize[0] * i, ptr + w * i, avctx->width);
  608.  
  609.         ptr += w * h;
  610.  
  611.         for (plane = 1; plane < 3; plane++) {
  612.             for (i = 0; i < avctx->height / 2; i++)
  613.                 memcpy(frame->data[plane] + frame->linesize[plane] * i, ptr + w / 2 * i, (avctx->width + 1) / 2);
  614.             ptr += w / 2 * h / 2;
  615.         }
  616.     }
  617.  
  618.     if (buffer->pts != MMAL_TIME_UNKNOWN) {
  619.         frame->pkt_pts = buffer->pts;
  620.         frame->pts = buffer->pts;
  621.     }
  622.  
  623. done:
  624.     return ret;
  625. }
  626.  
  627. // Fetch a decoded buffer and place it into the frame parameter.
  628. static int ffmmal_read_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame)
  629. {
  630.     MMALDecodeContext *ctx = avctx->priv_data;
  631.     MMAL_BUFFER_HEADER_T *buffer = NULL;
  632.     MMAL_STATUS_T status = 0;
  633.     int ret = 0;
  634.  
  635.     if (ctx->eos_received)
  636.         goto done;
  637.  
  638.     while (1) {
  639.         // To ensure decoding in lockstep with a constant delay between fed packets
  640.         // and output frames, we always wait until an output buffer is available.
  641.         // Except during start we don't know after how many input packets the decoder
  642.         // is going to return the first buffer, and we can't distinguish decoder
  643.         // being busy from decoder waiting for input. So just poll at the start and
  644.         // keep feeding new data to the buffer.
  645.         // We are pretty sure the decoder will produce output if we sent more input
  646.         // frames than what a h264 decoder could logically delay. This avoids too
  647.         // excessive buffering.
  648.         // We also wait if we sent eos, but didn't receive it yet (think of decoding
  649.         // stream with a very low number of frames).
  650.         if (ctx->frames_output || ctx->packets_sent > MAX_DELAYED_FRAMES ||
  651.             (ctx->packets_sent && ctx->eos_sent)) {
  652.             // MMAL will ignore broken input packets, which means the frame we
  653.             // expect here may never arrive. Dealing with this correctly is
  654.             // complicated, so here's a hack to avoid that it freezes forever
  655.             // in this unlikely situation.
  656.             buffer = mmal_queue_timedwait(ctx->queue_decoded_frames, 100);
  657.             if (!buffer) {
  658.                 av_log(avctx, AV_LOG_ERROR, "Did not get output frame from MMAL.\n");
  659.                 ret = AVERROR_UNKNOWN;
  660.                 goto done;
  661.             }
  662.         } else {
  663.             buffer = mmal_queue_get(ctx->queue_decoded_frames);
  664.             if (!buffer)
  665.                 goto done;
  666.         }
  667.  
  668.         ctx->eos_received |= !!(buffer->flags & MMAL_BUFFER_HEADER_FLAG_EOS);
  669.         if (ctx->eos_received)
  670.             goto done;
  671.  
  672.         if (buffer->cmd == MMAL_EVENT_FORMAT_CHANGED) {
  673.             MMAL_COMPONENT_T *decoder = ctx->decoder;
  674.             MMAL_EVENT_FORMAT_CHANGED_T *ev = mmal_event_format_changed_get(buffer);
  675.             MMAL_BUFFER_HEADER_T *stale_buffer;
  676.  
  677.             av_log(avctx, AV_LOG_INFO, "Changing output format.\n");
  678.  
  679.             if ((status = mmal_port_disable(decoder->output[0])))
  680.                 goto done;
  681.  
  682.             while ((stale_buffer = mmal_queue_get(ctx->queue_decoded_frames)))
  683.                 mmal_buffer_header_release(stale_buffer);
  684.  
  685.             mmal_format_copy(decoder->output[0]->format, ev->format);
  686.  
  687.             if ((ret = ffmal_update_format(avctx)) < 0)
  688.                 goto done;
  689.  
  690.             if ((status = mmal_port_enable(decoder->output[0], output_callback)))
  691.                 goto done;
  692.  
  693.             if ((ret = ffmmal_fill_output_port(avctx)) < 0)
  694.                 goto done;
  695.  
  696.             if ((ret = ffmmal_fill_input_port(avctx)) < 0)
  697.                 goto done;
  698.  
  699.             mmal_buffer_header_release(buffer);
  700.             continue;
  701.         } else if (buffer->cmd) {
  702.             char s[20];
  703.             av_get_codec_tag_string(s, sizeof(s), buffer->cmd);
  704.             av_log(avctx, AV_LOG_WARNING, "Unknown MMAL event %s on output port\n", s);
  705.             goto done;
  706.         } else if (buffer->length == 0) {
  707.             // Unused output buffer that got drained after format change.
  708.             mmal_buffer_header_release(buffer);
  709.             continue;
  710.         }
  711.  
  712.         ctx->frames_output++;
  713.  
  714.         if ((ret = ffmal_copy_frame(avctx, frame, buffer)) < 0)
  715.             goto done;
  716.  
  717.         *got_frame = 1;
  718.         break;
  719.     }
  720.  
  721. done:
  722.     if (buffer)
  723.         mmal_buffer_header_release(buffer);
  724.     if (status && ret >= 0)
  725.         ret = AVERROR_UNKNOWN;
  726.     return ret;
  727. }
  728.  
  729. static int ffmmal_decode(AVCodecContext *avctx, void *data, int *got_frame,
  730.                          AVPacket *avpkt)
  731. {
  732.     AVFrame *frame = data;
  733.     int ret = 0;
  734.  
  735.     if ((ret = ffmmal_add_packet(avctx, avpkt)) < 0)
  736.         return ret;
  737.  
  738.     if ((ret = ffmmal_fill_input_port(avctx)) < 0)
  739.         return ret;
  740.  
  741.     if ((ret = ffmmal_fill_output_port(avctx)) < 0)
  742.         return ret;
  743.  
  744.     if ((ret = ffmmal_read_frame(avctx, frame, got_frame)) < 0)
  745.         return ret;
  746.  
  747.     // ffmmal_read_frame() can block for a while. Since the decoder is
  748.     // asynchronous, it's a good idea to fill the ports again.
  749.  
  750.     if ((ret = ffmmal_fill_output_port(avctx)) < 0)
  751.         return ret;
  752.  
  753.     if ((ret = ffmmal_fill_input_port(avctx)) < 0)
  754.         return ret;
  755.  
  756.     return ret;
  757. }
  758.  
  759. AVHWAccel ff_h264_mmal_hwaccel = {
  760.     .name       = "h264_mmal",
  761.     .type       = AVMEDIA_TYPE_VIDEO,
  762.     .id         = AV_CODEC_ID_H264,
  763.     .pix_fmt    = AV_PIX_FMT_MMAL,
  764. };
  765.  
  766. static const AVOption options[]={
  767.     {"extra_buffers", "extra buffers", offsetof(MMALDecodeContext, extra_buffers), AV_OPT_TYPE_INT, {.i64 = 10}, 0, 256, 0},
  768.     {NULL}
  769. };
  770.  
  771. static const AVClass ffmmaldec_class = {
  772.     .class_name = "mmaldec",
  773.     .option     = options,
  774.     .version    = LIBAVUTIL_VERSION_INT,
  775. };
  776.  
  777. AVCodec ff_h264_mmal_decoder = {
  778.     .name           = "h264_mmal",
  779.     .long_name      = NULL_IF_CONFIG_SMALL("h264 (mmal)"),
  780.     .type           = AVMEDIA_TYPE_VIDEO,
  781.     .id             = AV_CODEC_ID_H264,
  782.     .priv_data_size = sizeof(MMALDecodeContext),
  783.     .init           = ffmmal_init_decoder,
  784.     .close          = ffmmal_close_decoder,
  785.     .decode         = ffmmal_decode,
  786.     .flush          = ffmmal_flush,
  787.     .priv_class     = &ffmmaldec_class,
  788.     .capabilities   = AV_CODEC_CAP_DELAY,
  789.     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_MMAL,
  790.                                                      AV_PIX_FMT_YUV420P,
  791.                                                      AV_PIX_FMT_NONE},
  792. };
  793.