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
  67   mkvparser::EBMLHeader header;
  68   long long pos = 0;
  69   if (header.Parse(reader, pos) < 0) {
  70     rewind_and_reset(webm_ctx, vpx_ctx);
  71     return 0;
  72   }
  73
  74   mkvparser::Segment* segment;
  75   if (mkvparser::Segment::CreateInstance(reader, pos, segment)) {
  76     rewind_and_reset(webm_ctx, vpx_ctx);
  77     return 0;
  78   }
  79   webm_ctx->segment = segment;
  80   if (segment->Load() < 0) {
  81     rewind_and_reset(webm_ctx, vpx_ctx);
  82     return 0;
  83   }
  84
  85   const mkvparser::Tracks *const tracks = segment->GetTracks();
  86   const mkvparser::VideoTrack* video_track = NULL;
  87   for (unsigned long i = 0; i < tracks->GetTracksCount(); ++i) {
  88     const mkvparser::Track* const track = tracks->GetTrackByIndex(i);
  89     if (track->GetType() == mkvparser::Track::kVideo) {
  90       video_track = static_cast<const mkvparser::VideoTrack*>(track);
  91       webm_ctx->video_track_index = track->GetNumber();
  92       break;
  93     }
  94   }
  95
  96   if (video_track == NULL) {
  97     rewind_and_reset(webm_ctx, vpx_ctx);
  98     return 0;
  99   }
 100
 101   if (!strncmp(video_track->GetCodecId(), "V_VP8", 5)) {
 102     vpx_ctx->fourcc = VP8_FOURCC;
 103   } else if (!strncmp(video_track->GetCodecId(), "V_VP9", 5)) {
 104     vpx_ctx->fourcc = VP9_FOURCC;
 105   } else {
 106     rewind_and_reset(webm_ctx, vpx_ctx);
 107     return 0;
 108   }
 109
 110   vpx_ctx->framerate.denominator = 0;
 111   vpx_ctx->framerate.numerator = 0;
 112   vpx_ctx->width = static_cast<uint32_t>(video_track->GetWidth());
 113   vpx_ctx->height = static_cast<uint32_t>(video_track->GetHeight());
 114
 115   get_first_cluster(webm_ctx);
 116
 117   return 1;
 118 }
 119
 120 int webm_read_frame(struct WebmInputContext *webm_ctx,
 121                     uint8_t **buffer,
 122                     size_t *bytes_in_buffer,
 123                     size_t *buffer_size) {
 124   mkvparser::Segment *const segment =
 125       reinterpret_cast<mkvparser::Segment*>(webm_ctx->segment);
 126   const mkvparser::Cluster* cluster =
 127       reinterpret_cast<const mkvparser::Cluster*>(webm_ctx->cluster);
 128   const mkvparser::Block *block =
 129       reinterpret_cast<const mkvparser::Block*>(webm_ctx->block);
 130   const mkvparser::BlockEntry *block_entry =
 131       reinterpret_cast<const mkvparser::BlockEntry*>(webm_ctx->block_entry);
 132   bool block_entry_eos = false;
 133   do {
 134     long status = 0;
 135     bool get_new_block = false;
 136     if (block_entry == NULL && !block_entry_eos) {
 137       status = cluster->GetFirst(block_entry);
 138       get_new_block = true;
 139     } else if (block_entry_eos || block_entry->EOS()) {
 140       cluster = segment->GetNext(cluster);
 141       if (cluster == NULL || cluster->EOS()) {
 142         *bytes_in_buffer = 0;
 143         return 1;
 144       }
 145       status = cluster->GetFirst(block_entry);
 146       block_entry_eos = false;
 147       get_new_block = true;
 148     } else if (block == NULL ||
 149                webm_ctx->block_frame_index == block->GetFrameCount() ||
 150                block->GetTrackNumber() != webm_ctx->video_track_index) {
 151       status = cluster->GetNext(block_entry, block_entry);
 152       if (block_entry == NULL || block_entry->EOS()) {
 153         block_entry_eos = true;
 154         continue;
 155       }
 156       get_new_block = true;
 157     }
 158     if (status) {
 159       return -1;
 160     }
 161     if (get_new_block) {
 162       block = block_entry->GetBlock();
 163       webm_ctx->block_frame_index = 0;
 164     }
 165   } while (block->GetTrackNumber() != webm_ctx->video_track_index ||
 166            block_entry_eos);
 167
 168   webm_ctx->cluster = cluster;
 169   webm_ctx->block_entry = block_entry;
 170   webm_ctx->block = block;
 171
 172   const mkvparser::Block::Frame& frame =
 173       block->GetFrame(webm_ctx->block_frame_index);
 174   ++webm_ctx->block_frame_index;
 175   if (frame.len > static_cast<long>(*buffer_size)) {
 176     delete[] *buffer;
 177     *buffer = new uint8_t[frame.len];
 178     if (*buffer == NULL) {
 179       return -1;
 180     }
 181     *buffer_size = frame.len;
 182     webm_ctx->buffer = *buffer;
 183   }
 184   *bytes_in_buffer = frame.len;
 185   webm_ctx->timestamp_ns = block->GetTime(cluster);
 186   webm_ctx->is_key_frame = block->IsKey();
 187
 188   mkvparser::MkvReader *const reader =
 189       reinterpret_cast<mkvparser::MkvReader*>(webm_ctx->reader);
 190   return frame.Read(reader, *buffer) ? -1 : 0;
 191 }
 192
 193 int webm_guess_framerate(struct WebmInputContext *webm_ctx,
 194                          struct VpxInputContext *vpx_ctx) {
 195   uint32_t i = 0;
 196   uint8_t *buffer = NULL;
 197   size_t bytes_in_buffer = 0;
 198   size_t buffer_size = 0;
 199   while (webm_ctx->timestamp_ns < 1000000000 && i < 50) {
 200     if (webm_read_frame(webm_ctx, &buffer, &bytes_in_buffer, &buffer_size)) {
 201       break;
 202     }
 203     ++i;
 204   }
 205   vpx_ctx->framerate.numerator = (i - 1) * 1000000;
 206   vpx_ctx->framerate.denominator =
 207       static_cast<int>(webm_ctx->timestamp_ns / 1000);
 208   delete[] buffer;
 209
 210   get_first_cluster(webm_ctx);
 211   webm_ctx->block = NULL;
 212   webm_ctx->block_entry = NULL;
 213   webm_ctx->block_frame_index = 0;
 214   webm_ctx->timestamp_ns = 0;
 215
 216   return 0;
 217 }
 218
 219 void webm_free(struct WebmInputContext *webm_ctx) {
 220   reset(webm_ctx);
 221 }