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- // Copyright (c) 2012 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/ffmpeg_glue.h"
- #include "base/check_op.h"
- #include "base/metrics/histogram_functions.h"
- #include "base/notreached.h"
- #include "media/base/container_names.h"
- #include "media/ffmpeg/ffmpeg_common.h"
- namespace media {
- // Internal buffer size used by AVIO for reading.
- // TODO(dalecurtis): Experiment with this buffer size and measure impact on
- // performance. Currently we want to use 32kb to preserve existing behavior
- // with the previous URLProtocol based approach.
- enum { kBufferSize = 32 * 1024 };
- static int AVIOReadOperation(void* opaque, uint8_t* buf, int buf_size) {
- return reinterpret_cast<FFmpegURLProtocol*>(opaque)->Read(buf_size, buf);
- }
- static int64_t AVIOSeekOperation(void* opaque, int64_t offset, int whence) {
- FFmpegURLProtocol* protocol = reinterpret_cast<FFmpegURLProtocol*>(opaque);
- int64_t new_offset = AVERROR(EIO);
- switch (whence) {
- case SEEK_SET:
- if (protocol->SetPosition(offset))
- protocol->GetPosition(&new_offset);
- break;
- case SEEK_CUR:
- int64_t pos;
- if (!protocol->GetPosition(&pos))
- break;
- if (protocol->SetPosition(pos + offset))
- protocol->GetPosition(&new_offset);
- break;
- case SEEK_END:
- int64_t size;
- if (!protocol->GetSize(&size))
- break;
- if (protocol->SetPosition(size + offset))
- protocol->GetPosition(&new_offset);
- break;
- case AVSEEK_SIZE:
- protocol->GetSize(&new_offset);
- break;
- default:
- NOTREACHED();
- }
- return new_offset;
- }
- static void LogContainer(bool is_local_file,
- container_names::MediaContainerName container) {
- base::UmaHistogramSparse("Media.DetectedContainer", container);
- if (is_local_file)
- base::UmaHistogramSparse("Media.DetectedContainer.Local", container);
- }
- FFmpegGlue::FFmpegGlue(FFmpegURLProtocol* protocol) {
- // Initialize an AVIOContext using our custom read and seek operations. Don't
- // keep pointers to the buffer since FFmpeg may reallocate it on the fly. It
- // will be cleaned up
- format_context_ = avformat_alloc_context();
- avio_context_.reset(avio_alloc_context(
- static_cast<unsigned char*>(av_malloc(kBufferSize)), kBufferSize, 0,
- protocol, &AVIOReadOperation, nullptr, &AVIOSeekOperation));
- // Ensure FFmpeg only tries to seek on resources we know to be seekable.
- avio_context_->seekable =
- protocol->IsStreaming() ? 0 : AVIO_SEEKABLE_NORMAL;
- // Ensure writing is disabled.
- avio_context_->write_flag = 0;
- // Tell the format context about our custom IO context. avformat_open_input()
- // will set the AVFMT_FLAG_CUSTOM_IO flag for us, but do so here to ensure an
- // early error state doesn't cause FFmpeg to free our resources in error.
- format_context_->flags |= AVFMT_FLAG_CUSTOM_IO;
- // Enable fast, but inaccurate seeks for MP3.
- format_context_->flags |= AVFMT_FLAG_FAST_SEEK;
- // Ensures format parsing errors will bail out. From an audit on 11/2017, all
- // instances were real failures. Solves bugs like http://crbug.com/710791.
- format_context_->error_recognition |= AV_EF_EXPLODE;
- format_context_->pb = avio_context_.get();
- }
- bool FFmpegGlue::OpenContext(bool is_local_file) {
- DCHECK(!open_called_) << "OpenContext() shouldn't be called twice.";
- // If avformat_open_input() is called we have to take a slightly different
- // destruction path to avoid double frees.
- open_called_ = true;
- // By passing nullptr for the filename (second parameter) we are telling
- // FFmpeg to use the AVIO context we setup from the AVFormatContext structure.
- const int ret =
- avformat_open_input(&format_context_, nullptr, nullptr, nullptr);
- // If FFmpeg can't identify the file, read the first 8k and attempt to guess
- // at the container type ourselves. This way we can track emergent formats.
- // Only try on AVERROR_INVALIDDATA to avoid running after I/O errors.
- if (ret == AVERROR_INVALIDDATA) {
- std::vector<uint8_t> buffer(8192);
- const int64_t pos = AVIOSeekOperation(avio_context_->opaque, 0, SEEK_SET);
- if (pos < 0)
- return false;
- const int num_read =
- AVIOReadOperation(avio_context_->opaque, buffer.data(), buffer.size());
- if (num_read < container_names::kMinimumContainerSize)
- return false;
- container_ = container_names::DetermineContainer(buffer.data(), num_read);
- LogContainer(is_local_file, container_);
- detected_hls_ =
- container_ == container_names::MediaContainerName::CONTAINER_HLS;
- return false;
- } else if (ret < 0) {
- return false;
- }
- // Rely on ffmpeg's parsing if we're able to succesfully open the file.
- if (strcmp(format_context_->iformat->name, "mov,mp4,m4a,3gp,3g2,mj2") == 0)
- container_ = container_names::CONTAINER_MOV;
- else if (strcmp(format_context_->iformat->name, "flac") == 0)
- container_ = container_names::CONTAINER_FLAC;
- else if (strcmp(format_context_->iformat->name, "matroska,webm") == 0)
- container_ = container_names::CONTAINER_WEBM;
- else if (strcmp(format_context_->iformat->name, "ogg") == 0)
- container_ = container_names::CONTAINER_OGG;
- else if (strcmp(format_context_->iformat->name, "wav") == 0)
- container_ = container_names::CONTAINER_WAV;
- else if (strcmp(format_context_->iformat->name, "aac") == 0)
- container_ = container_names::CONTAINER_AAC;
- else if (strcmp(format_context_->iformat->name, "mp3") == 0)
- container_ = container_names::CONTAINER_MP3;
- else if (strcmp(format_context_->iformat->name, "amr") == 0)
- container_ = container_names::CONTAINER_AMR;
- else if (strcmp(format_context_->iformat->name, "avi") == 0)
- container_ = container_names::CONTAINER_AVI;
- DCHECK_NE(container_, container_names::CONTAINER_UNKNOWN);
- LogContainer(is_local_file, container_);
- return true;
- }
- FFmpegGlue::~FFmpegGlue() {
- // In the event of avformat_open_input() failure, FFmpeg may sometimes free
- // our AVFormatContext behind the scenes, but leave the buffer alive. It will
- // helpfully set |format_context_| to nullptr in this case.
- if (!format_context_) {
- av_free(avio_context_->buffer);
- return;
- }
- // If avformat_open_input() hasn't been called, we should simply free the
- // AVFormatContext and buffer instead of using avformat_close_input().
- if (!open_called_) {
- avformat_free_context(format_context_);
- av_free(avio_context_->buffer);
- return;
- }
- avformat_close_input(&format_context_);
- av_free(avio_context_->buffer);
- }
- } // namespace media
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