webmdec.cc

   1 /*
   2  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #include "./webmdec.h"
  12
  13 #include <cstring>
  14 #include <cstdio>
  15
  16 #include "third_party/libwebm/mkvparser.hpp"
  17 #include "third_party/libwebm/mkvreader.hpp"
  18
  19 namespace {
  20
  21 void reset(struct WebmInputContext *const webm_ctx) {
  22   if (webm_ctx->reader != NULL) {
  23     mkvparser::MkvReader *const reader =
  24         reinterpret_cast<mkvparser::MkvReader*>(webm_ctx->reader);
  25     delete reader;
  26   }
  27   if (webm_ctx->segment != NULL) {
  28     mkvparser::Segment *const segment =
  29         reinterpret_cast<mkvparser::Segment*>(webm_ctx->segment);
  30     delete segment;
  31   }
  32   if (webm_ctx->buffer != NULL) {
  33     delete[] webm_ctx->buffer;
  34   }
  35   webm_ctx->reader = NULL;
  36   webm_ctx->segment = NULL;
  37   webm_ctx->buffer = NULL;
  38   webm_ctx->cluster = NULL;
  39   webm_ctx->block_entry = NULL;
  40   webm_ctx->block = NULL;
  41   webm_ctx->block_frame_index = 0;
  42   webm_ctx->video_track_index = 0;
  43   webm_ctx->timestamp_ns = 0;
  44   webm_ctx->is_key_frame = false;
  45 }
  46
  47 void get_first_cluster(struct WebmInputContext *const webm_ctx) {
  48   mkvparser::Segment *const segment =
  49       reinterpret_cast<mkvparser::Segment*>(webm_ctx->segment);
  50   const mkvparser::Cluster *const cluster = segment->GetFirst();
  51   webm_ctx->cluster = cluster;
  52 }
  53
  54 void rewind_and_reset(struct WebmInputContext *const webm_ctx,
  55                       struct VpxInputContext *const vpx_ctx) {
  56   rewind(vpx_ctx->file);
  57   reset(webm_ctx);
  58 }
  59
  60 }  // namespace
  61
  62 int file_is_webm(struct WebmInputContext *webm_ctx,
  63                  struct VpxInputContext *vpx_ctx) {
  64   mkvparser::MkvReader *const reader = new mkvparser::MkvReader(vpx_ctx->file);
  65   webm_ctx->reader = reader;
  66   webm_ctx->reached_eos = 0;
  67
  68   mkvparser::EBMLHeader header;
  69   long long pos = 0;
  70   if (header.Parse(reader, pos) < 0) {
  71     rewind_and_reset(webm_ctx, vpx_ctx);
  72     return 0;
  73   }
  74
  75   mkvparser::Segment* segment;
  76   if (mkvparser::Segment::CreateInstance(reader, pos, segment)) {
  77     rewind_and_reset(webm_ctx, vpx_ctx);
  78     return 0;
  79   }
  80   webm_ctx->segment = segment;
  81   if (segment->Load() < 0) {
  82     rewind_and_reset(webm_ctx, vpx_ctx);
  83     return 0;
  84   }
  85
  86   const mkvparser::Tracks *const tracks = segment->GetTracks();
  87   const mkvparser::VideoTrack* video_track = NULL;
  88   for (unsigned long i = 0; i < tracks->GetTracksCount(); ++i) {
  89     const mkvparser::Track* const track = tracks->GetTrackByIndex(i);
  90     if (track->GetType() == mkvparser::Track::kVideo) {
  91       video_track = static_cast<const mkvparser::VideoTrack*>(track);
  92       webm_ctx->video_track_index = track->GetNumber();
  93       break;
  94     }
  95   }
  96
  97   if (video_track == NULL) {
  98     rewind_and_reset(webm_ctx, vpx_ctx);
  99     return 0;
 100   }
 101
 102   if (!strncmp(video_track->GetCodecId(), "V_VP8", 5)) {
 103     vpx_ctx->fourcc = VP8_FOURCC;
 104   } else if (!strncmp(video_track->GetCodecId(), "V_VP9", 5)) {
 105     vpx_ctx->fourcc = VP9_FOURCC;
 106   } else {
 107     rewind_and_reset(webm_ctx, vpx_ctx);
 108     return 0;
 109   }
 110
 111   vpx_ctx->framerate.denominator = 0;
 112   vpx_ctx->framerate.numerator = 0;
 113   vpx_ctx->width = static_cast<uint32_t>(video_track->GetWidth());
 114   vpx_ctx->height = static_cast<uint32_t>(video_track->GetHeight());
 115
 116   get_first_cluster(webm_ctx);
 117
 118   return 1;
 119 }
 120
 121 int webm_read_frame(struct WebmInputContext *webm_ctx,
 122                     uint8_t **buffer,
 123                     size_t *bytes_in_buffer,
 124                     size_t *buffer_size) {
 125   // This check is needed for frame parallel decoding, in which case this
 126   // function could be called even after it has reached end of input stream.
 127   if (webm_ctx->reached_eos) {
 128     return 1;
 129   }
 130   mkvparser::Segment *const segment =
 131       reinterpret_cast<mkvparser::Segment*>(webm_ctx->segment);
 132   const mkvparser::Cluster* cluster =
 133       reinterpret_cast<const mkvparser::Cluster*>(webm_ctx->cluster);
 134   const mkvparser::Block *block =
 135       reinterpret_cast<const mkvparser::Block*>(webm_ctx->block);
 136   const mkvparser::BlockEntry *block_entry =
 137       reinterpret_cast<const mkvparser::BlockEntry*>(webm_ctx->block_entry);
 138   bool block_entry_eos = false;
 139   do {
 140     long status = 0;
 141     bool get_new_block = false;
 142     if (block_entry == NULL && !block_entry_eos) {
 143       status = cluster->GetFirst(block_entry);
 144       get_new_block = true;
 145     } else if (block_entry_eos || block_entry->EOS()) {
 146       cluster = segment->GetNext(cluster);
 147       if (cluster == NULL || cluster->EOS()) {
 148         *bytes_in_buffer = 0;
 149         webm_ctx->reached_eos = 1;
 150         return 1;
 151       }
 152       status = cluster->GetFirst(block_entry);
 153       block_entry_eos = false;
 154       get_new_block = true;
 155     } else if (block == NULL ||
 156                webm_ctx->block_frame_index == block->GetFrameCount() ||
 157                block->GetTrackNumber() != webm_ctx->video_track_index) {
 158       status = cluster->GetNext(block_entry, block_entry);
 159       if (block_entry == NULL || block_entry->EOS()) {
 160         block_entry_eos = true;
 161         continue;
 162       }
 163       get_new_block = true;
 164     }
 165     if (status) {
 166       return -1;
 167     }
 168     if (get_new_block) {
 169       block = block_entry->GetBlock();
 170       webm_ctx->block_frame_index = 0;
 171     }
 172   } while (block->GetTrackNumber() != webm_ctx->video_track_index ||
 173            block_entry_eos);
 174
 175   webm_ctx->cluster = cluster;
 176   webm_ctx->block_entry = block_entry;
 177   webm_ctx->block = block;
 178
 179   const mkvparser::Block::Frame& frame =
 180       block->GetFrame(webm_ctx->block_frame_index);
 181   ++webm_ctx->block_frame_index;
 182   if (frame.len > static_cast<long>(*buffer_size)) {
 183     delete[] *buffer;
 184     *buffer = new uint8_t[frame.len];
 185     if (*buffer == NULL) {
 186       return -1;
 187     }
 188     *buffer_size = frame.len;
 189     webm_ctx->buffer = *buffer;
 190   }
 191   *bytes_in_buffer = frame.len;
 192   webm_ctx->timestamp_ns = block->GetTime(cluster);
 193   webm_ctx->is_key_frame = block->IsKey();
 194
 195   mkvparser::MkvReader *const reader =
 196       reinterpret_cast<mkvparser::MkvReader*>(webm_ctx->reader);
 197   return frame.Read(reader, *buffer) ? -1 : 0;
 198 }
 199
 200 int webm_guess_framerate(struct WebmInputContext *webm_ctx,
 201                          struct VpxInputContext *vpx_ctx) {
 202   uint32_t i = 0;
 203   uint8_t *buffer = NULL;
 204   size_t bytes_in_buffer = 0;
 205   size_t buffer_size = 0;
 206   while (webm_ctx->timestamp_ns < 1000000000 && i < 50) {
 207     if (webm_read_frame(webm_ctx, &buffer, &bytes_in_buffer, &buffer_size)) {
 208       break;
 209     }
 210     ++i;
 211   }
 212   vpx_ctx->framerate.numerator = (i - 1) * 1000000;
 213   vpx_ctx->framerate.denominator =
 214       static_cast<int>(webm_ctx->timestamp_ns / 1000);
 215   delete[] buffer;
 216
 217   get_first_cluster(webm_ctx);
 218   webm_ctx->block = NULL;
 219   webm_ctx->block_entry = NULL;
 220   webm_ctx->block_frame_index = 0;
 221   webm_ctx->timestamp_ns = 0;
 222   webm_ctx->reached_eos = 0;
 223
 224   return 0;
 225 }
 226
 227 void webm_free(struct WebmInputContext *webm_ctx) {
 228   reset(webm_ctx);
 229 }