media/filters/ffmpeg_video_decoder.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/filters/ffmpeg_video_decoder.h"
   6
   7 #include <algorithm>
   8 #include <string>
   9
  10 #include "base/bind.h"
  11 #include "base/callback_helpers.h"
  12 #include "base/command_line.h"
  13 #include "base/location.h"
  14 #include "base/single_thread_task_runner.h"
  15 #include "base/strings/string_number_conversions.h"
  16 #include "media/base/bind_to_current_loop.h"
  17 #include "media/base/decoder_buffer.h"
  18 #include "media/base/limits.h"
  19 #include "media/base/media_switches.h"
  20 #include "media/base/pipeline.h"
  21 #include "media/base/video_frame.h"
  22 #include "media/base/video_util.h"
  23 #include "media/ffmpeg/ffmpeg_common.h"
  24 #include "media/filters/ffmpeg_glue.h"
  25
  26 namespace media {
  27
  28 // Always try to use three threads for video decoding.  There is little reason
  29 // not to since current day CPUs tend to be multi-core and we measured
  30 // performance benefits on older machines such as P4s with hyperthreading.
  31 //
  32 // Handling decoding on separate threads also frees up the pipeline thread to
  33 // continue processing. Although it'd be nice to have the option of a single
  34 // decoding thread, FFmpeg treats having one thread the same as having zero
  35 // threads (i.e., avcodec_decode_video() will execute on the calling thread).
  36 // Yet another reason for having two threads :)
  37 static const int kDecodeThreads = 2;
  38 static const int kMaxDecodeThreads = 16;
  39
  40 // Returns the number of threads given the FFmpeg CodecID. Also inspects the
  41 // command line for a valid --video-threads flag.
  42 static int GetThreadCount(AVCodecID codec_id) {
  43   // Refer to http://crbug.com/93932 for tsan suppressions on decoding.
  44   int decode_threads = kDecodeThreads;
  45
  46   const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
  47   std::string threads(cmd_line->GetSwitchValueASCII(switches::kVideoThreads));
  48   if (threads.empty() || !base::StringToInt(threads, &decode_threads))
  49     return decode_threads;
  50
  51   decode_threads = std::max(decode_threads, 0);
  52   decode_threads = std::min(decode_threads, kMaxDecodeThreads);
  53   return decode_threads;
  54 }
  55
  56 static int GetVideoBufferImpl(struct AVCodecContext* s,
  57                               AVFrame* frame,
  58                               int flags) {
  59   FFmpegVideoDecoder* decoder = static_cast<FFmpegVideoDecoder*>(s->opaque);
  60   return decoder->GetVideoBuffer(s, frame, flags);
  61 }
  62
  63 static void ReleaseVideoBufferImpl(void* opaque, uint8* data) {
  64   scoped_refptr<VideoFrame> video_frame;
  65   video_frame.swap(reinterpret_cast<VideoFrame**>(&opaque));
  66 }
  67
  68 FFmpegVideoDecoder::FFmpegVideoDecoder(
  69     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
  70     : task_runner_(task_runner), state_(kUninitialized),
  71       decode_nalus_(false) {}
  72
  73 int FFmpegVideoDecoder::GetVideoBuffer(struct AVCodecContext* codec_context,
  74                                        AVFrame* frame,
  75                                        int flags) {
  76   // Don't use |codec_context_| here! With threaded decoding,
  77   // it will contain unsynchronized width/height/pix_fmt values,
  78   // whereas |codec_context| contains the current threads's
  79   // updated width/height/pix_fmt, which can change for adaptive
  80   // content.
  81   const VideoPixelFormat format =
  82       AVPixelFormatToVideoPixelFormat(codec_context->pix_fmt);
  83
  84   if (format == PIXEL_FORMAT_UNKNOWN)
  85     return AVERROR(EINVAL);
  86   DCHECK(format == PIXEL_FORMAT_YV12 || format == PIXEL_FORMAT_YV16 ||
  87          format == PIXEL_FORMAT_YV24);
  88
  89   gfx::Size size(codec_context->width, codec_context->height);
  90   const int ret = av_image_check_size(size.width(), size.height(), 0, NULL);
  91   if (ret < 0)
  92     return ret;
  93
  94   gfx::Size natural_size;
  95   if (codec_context->sample_aspect_ratio.num > 0) {
  96     natural_size = GetNaturalSize(size,
  97                                   codec_context->sample_aspect_ratio.num,
  98                                   codec_context->sample_aspect_ratio.den);
  99   } else {
 100     natural_size = config_.natural_size();
 101   }
 102
 103   // FFmpeg has specific requirements on the allocation size of the frame.  The
 104   // following logic replicates FFmpeg's allocation strategy to ensure buffers
 105   // are not overread / overwritten.  See ff_init_buffer_info() for details.
 106   //
 107   // When lowres is non-zero, dimensions should be divided by 2^(lowres), but
 108   // since we don't use this, just DCHECK that it's zero.
 109   DCHECK_EQ(codec_context->lowres, 0);
 110   gfx::Size coded_size(std::max(size.width(), codec_context->coded_width),
 111                        std::max(size.height(), codec_context->coded_height));
 112
 113   if (!VideoFrame::IsValidConfig(format, VideoFrame::STORAGE_UNKNOWN,
 114                                  coded_size, gfx::Rect(size), natural_size)) {
 115     return AVERROR(EINVAL);
 116   }
 117
 118   // FFmpeg expects the initialize allocation to be zero-initialized.  Failure
 119   // to do so can lead to unitialized value usage.  See http://crbug.com/390941
 120   scoped_refptr<VideoFrame> video_frame = frame_pool_.CreateFrame(
 121       format, coded_size, gfx::Rect(size), natural_size, kNoTimestamp());
 122
 123   // Prefer the color space from the codec context. If it's not specified (or is
 124   // set to an unsupported value), fall back on the value from the config.
 125   ColorSpace color_space = AVColorSpaceToColorSpace(codec_context->colorspace,
 126                                                     codec_context->color_range);
 127   if (color_space == COLOR_SPACE_UNSPECIFIED)
 128     color_space = config_.color_space();
 129   video_frame->metadata()->SetInteger(VideoFrameMetadata::COLOR_SPACE,
 130                                       color_space);
 131
 132   for (size_t i = 0; i < VideoFrame::NumPlanes(video_frame->format()); i++) {
 133     frame->data[i] = video_frame->data(i);
 134     frame->linesize[i] = video_frame->stride(i);
 135   }
 136
 137   frame->width = coded_size.width();
 138   frame->height = coded_size.height();
 139   frame->format = codec_context->pix_fmt;
 140   frame->reordered_opaque = codec_context->reordered_opaque;
 141
 142   // Now create an AVBufferRef for the data just allocated. It will own the
 143   // reference to the VideoFrame object.
 144   void* opaque = NULL;
 145   video_frame.swap(reinterpret_cast<VideoFrame**>(&opaque));
 146   frame->buf[0] =
 147       av_buffer_create(frame->data[0],
 148                        VideoFrame::AllocationSize(format, coded_size),
 149                        ReleaseVideoBufferImpl,
 150                        opaque,
 151                        0);
 152   return 0;
 153 }
 154
 155 std::string FFmpegVideoDecoder::GetDisplayName() const {
 156   return "FFmpegVideoDecoder";
 157 }
 158
 159 void FFmpegVideoDecoder::Initialize(const VideoDecoderConfig& config,
 160                                     bool low_delay,
 161                                     const InitCB& init_cb,
 162                                     const OutputCB& output_cb) {
 163   DCHECK(task_runner_->BelongsToCurrentThread());
 164   DCHECK(!config.is_encrypted());
 165   DCHECK(!output_cb.is_null());
 166
 167   FFmpegGlue::InitializeFFmpeg();
 168
 169   config_ = config;
 170   InitCB bound_init_cb = BindToCurrentLoop(init_cb);
 171
 172   if (!config.IsValidConfig() || !ConfigureDecoder(low_delay)) {
 173     bound_init_cb.Run(false);
 174     return;
 175   }
 176
 177   output_cb_ = BindToCurrentLoop(output_cb);
 178
 179   // Success!
 180   state_ = kNormal;
 181   bound_init_cb.Run(true);
 182 }
 183
 184 void FFmpegVideoDecoder::Decode(const scoped_refptr<DecoderBuffer>& buffer,
 185                                 const DecodeCB& decode_cb) {
 186   DCHECK(task_runner_->BelongsToCurrentThread());
 187   DCHECK(buffer.get());
 188   DCHECK(!decode_cb.is_null());
 189   CHECK_NE(state_, kUninitialized);
 190
 191   DecodeCB decode_cb_bound = BindToCurrentLoop(decode_cb);
 192
 193   if (state_ == kError) {
 194     decode_cb_bound.Run(kDecodeError);
 195     return;
 196   }
 197
 198   if (state_ == kDecodeFinished) {
 199     decode_cb_bound.Run(kOk);
 200     return;
 201   }
 202
 203   DCHECK_EQ(state_, kNormal);
 204
 205   // During decode, because reads are issued asynchronously, it is possible to
 206   // receive multiple end of stream buffers since each decode is acked. When the
 207   // first end of stream buffer is read, FFmpeg may still have frames queued
 208   // up in the decoder so we need to go through the decode loop until it stops
 209   // giving sensible data.  After that, the decoder should output empty
 210   // frames.  There are three states the decoder can be in:
 211   //
 212   //   kNormal: This is the starting state. Buffers are decoded. Decode errors
 213   //            are discarded.
 214   //   kDecodeFinished: All calls return empty frames.
 215   //   kError: Unexpected error happened.
 216   //
 217   // These are the possible state transitions.
 218   //
 219   // kNormal -> kDecodeFinished:
 220   //     When EOS buffer is received and the codec has been flushed.
 221   // kNormal -> kError:
 222   //     A decoding error occurs and decoding needs to stop.
 223   // (any state) -> kNormal:
 224   //     Any time Reset() is called.
 225
 226   bool has_produced_frame;
 227   do {
 228     has_produced_frame = false;
 229     if (!FFmpegDecode(buffer, &has_produced_frame)) {
 230       state_ = kError;
 231       decode_cb_bound.Run(kDecodeError);
 232       return;
 233     }
 234     // Repeat to flush the decoder after receiving EOS buffer.
 235   } while (buffer->end_of_stream() && has_produced_frame);
 236
 237   if (buffer->end_of_stream())
 238     state_ = kDecodeFinished;
 239
 240   // VideoDecoderShim expects that |decode_cb| is called only after
 241   // |output_cb_|.
 242   decode_cb_bound.Run(kOk);
 243 }
 244
 245 void FFmpegVideoDecoder::Reset(const base::Closure& closure) {
 246   DCHECK(task_runner_->BelongsToCurrentThread());
 247
 248   avcodec_flush_buffers(codec_context_.get());
 249   state_ = kNormal;
 250   task_runner_->PostTask(FROM_HERE, closure);
 251 }
 252
 253 FFmpegVideoDecoder::~FFmpegVideoDecoder() {
 254   DCHECK(task_runner_->BelongsToCurrentThread());
 255
 256   if (state_ != kUninitialized)
 257     ReleaseFFmpegResources();
 258 }
 259
 260 bool FFmpegVideoDecoder::FFmpegDecode(
 261     const scoped_refptr<DecoderBuffer>& buffer,
 262     bool* has_produced_frame) {
 263   DCHECK(!*has_produced_frame);
 264
 265   // Create a packet for input data.
 266   // Due to FFmpeg API changes we no longer have const read-only pointers.
 267   AVPacket packet;
 268   av_init_packet(&packet);
 269   if (buffer->end_of_stream()) {
 270     packet.data = NULL;
 271     packet.size = 0;
 272   } else {
 273     packet.data = const_cast<uint8*>(buffer->data());
 274     packet.size = buffer->data_size();
 275
 276     // Let FFmpeg handle presentation timestamp reordering.
 277     codec_context_->reordered_opaque = buffer->timestamp().InMicroseconds();
 278   }
 279
 280   int frame_decoded = 0;
 281   int result = avcodec_decode_video2(codec_context_.get(),
 282                                      av_frame_.get(),
 283                                      &frame_decoded,
 284                                      &packet);
 285   // Log the problem if we can't decode a video frame and exit early.
 286   if (result < 0) {
 287     LOG(ERROR) << "Error decoding video: " << buffer->AsHumanReadableString();
 288     return false;
 289   }
 290
 291   // FFmpeg says some codecs might have multiple frames per packet.  Previous
 292   // discussions with rbultje@ indicate this shouldn't be true for the codecs
 293   // we use.
 294   DCHECK_EQ(result, packet.size);
 295
 296   // If no frame was produced then signal that more data is required to
 297   // produce more frames. This can happen under two circumstances:
 298   //   1) Decoder was recently initialized/flushed
 299   //   2) End of stream was reached and all internal frames have been output
 300   if (frame_decoded == 0) {
 301     return true;
 302   }
 303
 304   // TODO(fbarchard): Work around for FFmpeg http://crbug.com/27675
 305   // The decoder is in a bad state and not decoding correctly.
 306   // Checking for NULL avoids a crash in CopyPlane().
 307   if (!av_frame_->data[VideoFrame::kYPlane] ||
 308       !av_frame_->data[VideoFrame::kUPlane] ||
 309       !av_frame_->data[VideoFrame::kVPlane]) {
 310     LOG(ERROR) << "Video frame was produced yet has invalid frame data.";
 311     av_frame_unref(av_frame_.get());
 312     return false;
 313   }
 314
 315   scoped_refptr<VideoFrame> frame =
 316       reinterpret_cast<VideoFrame*>(av_buffer_get_opaque(av_frame_->buf[0]));
 317   frame->set_timestamp(
 318       base::TimeDelta::FromMicroseconds(av_frame_->reordered_opaque));
 319   *has_produced_frame = true;
 320   output_cb_.Run(frame);
 321
 322   av_frame_unref(av_frame_.get());
 323   return true;
 324 }
 325
 326 void FFmpegVideoDecoder::ReleaseFFmpegResources() {
 327   codec_context_.reset();
 328   av_frame_.reset();
 329 }
 330
 331 bool FFmpegVideoDecoder::ConfigureDecoder(bool low_delay) {
 332   // Release existing decoder resources if necessary.
 333   ReleaseFFmpegResources();
 334
 335   // Initialize AVCodecContext structure.
 336   codec_context_.reset(avcodec_alloc_context3(NULL));
 337   VideoDecoderConfigToAVCodecContext(config_, codec_context_.get());
 338
 339   codec_context_->thread_count = GetThreadCount(codec_context_->codec_id);
 340   codec_context_->thread_type = low_delay ? FF_THREAD_SLICE : FF_THREAD_FRAME;
 341   codec_context_->opaque = this;
 342   codec_context_->flags |= CODEC_FLAG_EMU_EDGE;
 343   codec_context_->get_buffer2 = GetVideoBufferImpl;
 344   codec_context_->refcounted_frames = 1;
 345
 346   if (decode_nalus_)
 347     codec_context_->flags2 |= CODEC_FLAG2_CHUNKS;
 348
 349   AVCodec* codec = avcodec_find_decoder(codec_context_->codec_id);
 350   if (!codec || avcodec_open2(codec_context_.get(), codec, NULL) < 0) {
 351     ReleaseFFmpegResources();
 352     return false;
 353   }
 354
 355   av_frame_.reset(av_frame_alloc());
 356   return true;
 357 }
 358
 359 }  // namespace media