Implement WebKitClientImpl::loadAudioResource() to decode in-memory audio fil...

media/filters/audio_file_reader.cc

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/filters/audio_file_reader.h"
+
+#include <string>
+#include "base/basictypes.h"
+#include "base/string_util.h"
+#include "base/time.h"
+#include "media/audio/audio_util.h"
+#include "media/base/filters.h"
+#include "media/ffmpeg/ffmpeg_common.h"
+#include "media/ffmpeg/ffmpeg_util.h"
+#include "media/filters/ffmpeg_glue.h"
+
+namespace media {
+
+AudioFileReader::AudioFileReader(FFmpegURLProtocol* protocol)
+  : protocol_(protocol),

[scherkus (not reviewing), 2010/12/11 02:31:12]

indent this by extra 2 spaces

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+    format_context_(NULL),
+    codec_context_(NULL),
+    codec_(NULL) {
+}
+
+AudioFileReader::~AudioFileReader() {
+  Close();
+}
+
+int AudioFileReader::channels() const {
+  return codec_context_->channels;
+}
+
+int AudioFileReader::sample_rate() const {
+  return codec_context_->sample_rate;
+}
+
+base::TimeDelta AudioFileReader::duration() const {
+  const AVRational av_time_base = {1, AV_TIME_BASE};
+  return ConvertTimestamp(av_time_base, format_context_->duration);
+}
+
+int64 AudioFileReader::number_of_frames() const {
+  return duration().InSecondsF() * sample_rate();
+}
+
+bool AudioFileReader::Open() {
+  // Add our data reader to the protocol list and get our unique key.
+  std::string key = FFmpegGlue::get()->AddProtocol(protocol_);
+
+  // Open FFmpeg AVFormatContext.
+  DCHECK(!format_context_);
+  AVFormatContext* context = NULL;
+
+  int result = av_open_input_file(&context, key.c_str(), NULL, 0, NULL);
+
+  // Remove our data reader from protocol list since av_open_input_file() setup
+  // the AVFormatContext with the data reader.
+  FFmpegGlue::get()->RemoveProtocol(protocol_);
+
+  if (result) {
+      DLOG(WARNING)

[scherkus (not reviewing), 2010/12/11 02:31:12]

de-indent by 2 spaces

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+          << "AudioFileReader::Open() : error in av_open_input_file() -"
+          << " result: " << result;
+      return false;
+  }
+
+  DCHECK(context);
+  format_context_ = context;
+
+  // Get the codec context.
+  codec_context_ = NULL;
+  for (unsigned i = 0; i < format_context_->nb_streams; ++i) {
+    AVCodecContext* c = format_context_->streams[i]->codec;
+    if (c->codec_type == CODEC_TYPE_AUDIO) {
+      codec_context_ = c;
+      break;
+    }
+  }
+
+  // Get the codec.
+  if (codec_context_) {
+    av_find_stream_info(format_context_);
+    codec_ = avcodec_find_decoder(codec_context_->codec_id);
+    if (codec_) {
+      if ((result = avcodec_open(codec_context_, codec_)) < 0) {
+        DLOG(WARNING) << "AudioFileReader::Open() : could not open codec -"
+            << " result: " << result;
+        return false;
+      }
+
+      result = av_seek_frame(format_context_, 0, 0, 0);
+    }
+  } else {
+    return false;

[scherkus (not reviewing), 2010/12/11 02:31:12]

I'd flip this condition around and simply exit early to avoid nesting

if (!codec_context_)
  return false

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+  }
+
+  return true;
+}
+
+void AudioFileReader::Close() {
+  if (codec_context_ && codec_) {

[scherkus (not reviewing), 2010/12/11 02:31:12]

nit: the rest of this file seems to not include { } on one-line if statements

I don't prefer either way but consistency is all good in my book so let's remove
the { }!!!

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+    avcodec_close(codec_context_);
+  }
+  codec_context_ = NULL;
+  codec_ = NULL;
+
+  if (format_context_) {
+      av_close_input_file(format_context_);

[scherkus (not reviewing), 2010/12/11 02:31:12]

de-indent by 2 spaces

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+      format_context_ = NULL;
+  }
+}
+
+bool AudioFileReader::Read(const std::vector<float*>& audio_data,
+                           size_t number_of_frames) {
+  unsigned number_of_channels = channels();

[scherkus (not reviewing), 2010/12/11 02:31:12]

we haven't used unsigned anywhere in the media code, but when it calls for it
(as it does in this case as you're comparing it to std::vector::size()), just
use size_t

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+  DCHECK_EQ(audio_data.size(), number_of_channels);
+  if (audio_data.size() != number_of_channels)
+    return false;
+
+  DCHECK(format_context_ && codec_context_);
+  if (!format_context_ || !codec_context_) {
+    DLOG(WARNING) << "AudioFileReader::Read() : reader is not opened!";
+    return false;
+  }
+
+  int16* output_buffer =

[scherkus (not reviewing), 2010/12/11 02:31:12]

crazy ffmpeg stuff: you must use av_malloc()!!

otherwise things may explode for reasons I won't get into 

would also highly recommend using ScopedPtrAVFree from
media/ffmpeg/ffmpeg_common.h

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+    static_cast<int16*>(malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE));

[scherkus (not reviewing), 2010/12/11 02:31:12]

indent by extra 2 spaces

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+
+  // Read until we hit EOF or we've read the requested number of frames.
+  AVPacket avpkt;
+  av_init_packet(&avpkt);
+
+  int result = 0;
+  unsigned current_frame = 0;

[scherkus (not reviewing), 2010/12/11 02:31:12]

unsigned -> size_t

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+
+  while (current_frame < number_of_frames
+      && (result = av_read_frame(format_context_, &avpkt)) >= 0) {

[scherkus (not reviewing), 2010/12/11 02:31:12]

nit: && should be at end of last line + following line should be wrapped at (

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+    int out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
+    result = avcodec_decode_audio3(codec_context_,
+                                   output_buffer,
+                                   &out_size,
+                                   &avpkt);
+
+    if (result < 0) {
+      DLOG(WARNING)
+          << "AudioFileReader::Read() : error in avcodec_decode_audio3() -"
+          << result;
+      free(output_buffer);
+      return false;
+    }
+
+    // Determine the number of sample-frames we just decoded.
+    size_t sample_byte_size =
+      av_get_bits_per_sample_fmt(codec_context_->sample_fmt) >> 3;

[scherkus (not reviewing), 2010/12/11 02:31:12]

indent by extra 2 spaces

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+    unsigned frames_read = out_size / (number_of_channels * sample_byte_size);

[scherkus (not reviewing), 2010/12/11 02:31:12]

unsigned -> size_t

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+
+    // Truncate, if necessary, if the destination isn't big enough.
+    if (current_frame + frames_read > number_of_frames) {
+      frames_read = static_cast<int>(number_of_frames) - current_frame;

[scherkus (not reviewing), 2010/12/11 02:31:12]

is cast needed here?  it looks like frames_read, number_of_frames, and
current_frame are all of type size_t

also remove { } 

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+    }
+
+    // Deinterleave each channel and convert to 32bit floating-point
+    // with nominal range -1.0 -> +1.0.
+    for (unsigned channel_index = 0; channel_index < number_of_channels;

[scherkus (not reviewing), 2010/12/11 02:31:12]

unsigned -> size_t
OR
unsinged -> int, number_of_channels -> channels()

take your pick (I think the int version will mesh with the
DeinterleaveAudioChannel() method)

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+         ++channel_index) {
+      if (!DeinterleaveAudioChannel(output_buffer,
+                                    audio_data[channel_index] + current_frame,
+                                    codec_context_->sample_fmt,
+                                    number_of_channels,
+                                    channel_index,
+                                    frames_read)) {
+        DLOG(WARNING)
+            << "AudioFileReader::Read() : Unsupported sample format : "
+            << codec_context_->sample_fmt
+            << " codec_->id : " << codec_->id;
+        return false;
+      }
+    }
+
+    current_frame += frames_read;
+  }
+
+  free(output_buffer);
+  return true;  // success

[scherkus (not reviewing), 2010/12/11 02:31:12]

no need for comment

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+}
+
+InMemoryDataReader::InMemoryDataReader(const char* data, int64 size)
+  : data_(data),

[scherkus (not reviewing), 2010/12/11 02:31:12]

indent by 2 extra spaces

[Chris Rogers, 2010/12/13 20:25:27]

Done.

+    size_(size),
+    position_(0) {
+}
+
+int InMemoryDataReader::Read(int size, uint8* data) {
+  if (size < 0)
+    return -1;
+
+  int64 available_bytes = size_ - position_;
+  if (size > available_bytes)
+    size = available_bytes;
+
+  memcpy(data, data_ + position_, size);
+  position_ += size;
+  return size;
+}
+
+bool InMemoryDataReader::GetPosition(int64* position_out) {
+  if (position_out)
+    *position_out = position_;
+  return true;
+}
+
+bool InMemoryDataReader::SetPosition(int64 position) {
+  if (position >= size_)
+    return false;
+  position_ = position;
+  return true;
+}
+
+bool InMemoryDataReader::GetSize(int64* size_out) {
+  if (size_out)
+    *size_out = size_;
+  return true;
+}
+
+bool InMemoryDataReader::IsStreaming() {
+  return false;
+}
+
+}  // namespace media