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       PixelFormatToVideoPixelFormat(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   scoped_refptr<VideoFrame> video_frame = frame_pool_.CreateFrame(
 119       format, coded_size, gfx::Rect(size), natural_size, kNoTimestamp());
 120 #if defined(MEMORY_SANITIZER)
 121   MSAN_UNPOISON(video_frame->data(0),
 122                 VideoFrame::AllocationSize(format, coded_size));
 123 #endif
 124
 125   // Prefer the color space from the codec context. If it's not specified (or is
 126   // set to an unsupported value), fall back on the value from the config.
 127   ColorSpace color_space = AVColorSpaceToColorSpace(codec_context->colorspace,
 128                                                     codec_context->color_range);
 129   if (color_space == COLOR_SPACE_UNSPECIFIED)
 130     color_space = config_.color_space();
 131   video_frame->metadata()->SetInteger(VideoFrameMetadata::COLOR_SPACE,
 132                                       color_space);
 133
 134   for (int i = 0; i < 3; i++) {
 135     frame->data[i] = video_frame->data(i);
 136     frame->linesize[i] = video_frame->stride(i);
 137   }
 138
 139   frame->width = coded_size.width();
 140   frame->height = coded_size.height();
 141   frame->format = codec_context->pix_fmt;
 142   frame->reordered_opaque = codec_context->reordered_opaque;
 143
 144   // Now create an AVBufferRef for the data just allocated. It will own the
 145   // reference to the VideoFrame object.
 146   void* opaque = NULL;
 147   video_frame.swap(reinterpret_cast<VideoFrame**>(&opaque));
 148   frame->buf[0] =
 149       av_buffer_create(frame->data[0],
 150                        VideoFrame::AllocationSize(format, coded_size),
 151                        ReleaseVideoBufferImpl,
 152                        opaque,
 153                        0);
 154   return 0;
 155 }
 156
 157 std::string FFmpegVideoDecoder::GetDisplayName() const {
 158   return "FFmpegVideoDecoder";
 159 }
 160
 161 void FFmpegVideoDecoder::Initialize(const VideoDecoderConfig& config,
 162                                     bool low_delay,
 163                                     const InitCB& init_cb,
 164                                     const OutputCB& output_cb) {
 165   DCHECK(task_runner_->BelongsToCurrentThread());
 166   DCHECK(!config.is_encrypted());
 167   DCHECK(!output_cb.is_null());
 168
 169   FFmpegGlue::InitializeFFmpeg();
 170
 171   config_ = config;
 172   InitCB bound_init_cb = BindToCurrentLoop(init_cb);
 173
 174   if (!config.IsValidConfig() || !ConfigureDecoder(low_delay)) {
 175     bound_init_cb.Run(false);
 176     return;
 177   }
 178
 179   output_cb_ = BindToCurrentLoop(output_cb);
 180
 181   // Success!
 182   state_ = kNormal;
 183   bound_init_cb.Run(true);
 184 }
 185
 186 void FFmpegVideoDecoder::Decode(const scoped_refptr<DecoderBuffer>& buffer,
 187                                 const DecodeCB& decode_cb) {
 188   DCHECK(task_runner_->BelongsToCurrentThread());
 189   DCHECK(buffer.get());
 190   DCHECK(!decode_cb.is_null());
 191   CHECK_NE(state_, kUninitialized);
 192
 193   DecodeCB decode_cb_bound = BindToCurrentLoop(decode_cb);
 194
 195   if (state_ == kError) {
 196     decode_cb_bound.Run(kDecodeError);
 197     return;
 198   }
 199
 200   if (state_ == kDecodeFinished) {
 201     decode_cb_bound.Run(kOk);
 202     return;
 203   }
 204
 205   DCHECK_EQ(state_, kNormal);
 206
 207   // During decode, because reads are issued asynchronously, it is possible to
 208   // receive multiple end of stream buffers since each decode is acked. When the
 209   // first end of stream buffer is read, FFmpeg may still have frames queued
 210   // up in the decoder so we need to go through the decode loop until it stops
 211   // giving sensible data.  After that, the decoder should output empty
 212   // frames.  There are three states the decoder can be in:
 213   //
 214   //   kNormal: This is the starting state. Buffers are decoded. Decode errors
 215   //            are discarded.
 216   //   kDecodeFinished: All calls return empty frames.
 217   //   kError: Unexpected error happened.
 218   //
 219   // These are the possible state transitions.
 220   //
 221   // kNormal -> kDecodeFinished:
 222   //     When EOS buffer is received and the codec has been flushed.
 223   // kNormal -> kError:
 224   //     A decoding error occurs and decoding needs to stop.
 225   // (any state) -> kNormal:
 226   //     Any time Reset() is called.
 227
 228   bool has_produced_frame;
 229   do {
 230     has_produced_frame = false;
 231     if (!FFmpegDecode(buffer, &has_produced_frame)) {
 232       state_ = kError;
 233       decode_cb_bound.Run(kDecodeError);
 234       return;
 235     }
 236     // Repeat to flush the decoder after receiving EOS buffer.
 237   } while (buffer->end_of_stream() && has_produced_frame);
 238
 239   if (buffer->end_of_stream())
 240     state_ = kDecodeFinished;
 241
 242   // VideoDecoderShim expects that |decode_cb| is called only after
 243   // |output_cb_|.
 244   decode_cb_bound.Run(kOk);
 245 }
 246
 247 void FFmpegVideoDecoder::Reset(const base::Closure& closure) {
 248   DCHECK(task_runner_->BelongsToCurrentThread());
 249
 250   avcodec_flush_buffers(codec_context_.get());
 251   state_ = kNormal;
 252   task_runner_->PostTask(FROM_HERE, closure);
 253 }
 254
 255 FFmpegVideoDecoder::~FFmpegVideoDecoder() {
 256   DCHECK(task_runner_->BelongsToCurrentThread());
 257
 258   if (state_ != kUninitialized)
 259     ReleaseFFmpegResources();
 260 }
 261
 262 bool FFmpegVideoDecoder::FFmpegDecode(
 263     const scoped_refptr<DecoderBuffer>& buffer,
 264     bool* has_produced_frame) {
 265   DCHECK(!*has_produced_frame);
 266
 267   // Create a packet for input data.
 268   // Due to FFmpeg API changes we no longer have const read-only pointers.
 269   AVPacket packet;
 270   av_init_packet(&packet);
 271   if (buffer->end_of_stream()) {
 272     packet.data = NULL;
 273     packet.size = 0;
 274   } else {
 275     packet.data = const_cast<uint8*>(buffer->data());
 276     packet.size = buffer->data_size();
 277
 278     // Let FFmpeg handle presentation timestamp reordering.
 279     codec_context_->reordered_opaque = buffer->timestamp().InMicroseconds();
 280   }
 281
 282   int frame_decoded = 0;
 283   int result = avcodec_decode_video2(codec_context_.get(),
 284                                      av_frame_.get(),
 285                                      &frame_decoded,
 286                                      &packet);
 287   // Log the problem if we can't decode a video frame and exit early.
 288   if (result < 0) {
 289     LOG(ERROR) << "Error decoding video: " << buffer->AsHumanReadableString();
 290     return false;
 291   }
 292
 293   // FFmpeg says some codecs might have multiple frames per packet.  Previous
 294   // discussions with rbultje@ indicate this shouldn't be true for the codecs
 295   // we use.
 296   DCHECK_EQ(result, packet.size);
 297
 298   // If no frame was produced then signal that more data is required to
 299   // produce more frames. This can happen under two circumstances:
 300   //   1) Decoder was recently initialized/flushed
 301   //   2) End of stream was reached and all internal frames have been output
 302   if (frame_decoded == 0) {
 303     return true;
 304   }
 305
 306   // TODO(fbarchard): Work around for FFmpeg http://crbug.com/27675
 307   // The decoder is in a bad state and not decoding correctly.
 308   // Checking for NULL avoids a crash in CopyPlane().
 309   if (!av_frame_->data[VideoFrame::kYPlane] ||
 310       !av_frame_->data[VideoFrame::kUPlane] ||
 311       !av_frame_->data[VideoFrame::kVPlane]) {
 312     LOG(ERROR) << "Video frame was produced yet has invalid frame data.";
 313     av_frame_unref(av_frame_.get());
 314     return false;
 315   }
 316
 317   scoped_refptr<VideoFrame> frame =
 318       reinterpret_cast<VideoFrame*>(av_buffer_get_opaque(av_frame_->buf[0]));
 319   frame->set_timestamp(
 320       base::TimeDelta::FromMicroseconds(av_frame_->reordered_opaque));
 321   *has_produced_frame = true;
 322   output_cb_.Run(frame);
 323
 324   av_frame_unref(av_frame_.get());
 325   return true;
 326 }
 327
 328 void FFmpegVideoDecoder::ReleaseFFmpegResources() {
 329   codec_context_.reset();
 330   av_frame_.reset();
 331 }
 332
 333 bool FFmpegVideoDecoder::ConfigureDecoder(bool low_delay) {
 334   // Release existing decoder resources if necessary.
 335   ReleaseFFmpegResources();
 336
 337   // Initialize AVCodecContext structure.
 338   codec_context_.reset(avcodec_alloc_context3(NULL));
 339   VideoDecoderConfigToAVCodecContext(config_, codec_context_.get());
 340
 341   codec_context_->thread_count = GetThreadCount(codec_context_->codec_id);
 342   codec_context_->thread_type = low_delay ? FF_THREAD_SLICE : FF_THREAD_FRAME;
 343   codec_context_->opaque = this;
 344   codec_context_->flags |= CODEC_FLAG_EMU_EDGE;
 345   codec_context_->get_buffer2 = GetVideoBufferImpl;
 346   codec_context_->refcounted_frames = 1;
 347
 348   if (decode_nalus_)
 349     codec_context_->flags2 |= CODEC_FLAG2_CHUNKS;
 350
 351   AVCodec* codec = avcodec_find_decoder(codec_context_->codec_id);
 352   if (!codec || avcodec_open2(codec_context_.get(), codec, NULL) < 0) {
 353     ReleaseFFmpegResources();
 354     return false;
 355   }
 356
 357   av_frame_.reset(av_frame_alloc());
 358   return true;
 359 }
 360
 361 }  // namespace media