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// Copyright (c) 2011 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.
#ifndef MEDIA_BASE_H264_BITSTREAM_CONVERTER_H_
#define MEDIA_BASE_H264_BITSTREAM_CONVERTER_H_
#include "base/basictypes.h"
namespace media {
// H264BitstreamConverter is a class to convert H.264 bitstream from
// MP4 format (as specified in ISO/IEC 14496-15) into H.264 bytestream
// (as specified in ISO/IEC 14496-10 Annex B).
class H264BitstreamConverter {
public:
H264BitstreamConverter();
~H264BitstreamConverter();
// Parses the global AVCDecoderConfigurationRecord from the file format's
// headers. Converter will remember the field length from the configuration
// headers after this.
//
// Parameters
// configuration_record
// Pointer to buffer containing AVCDecoderConfigurationRecord.
// configuration_record_size
// Size of the buffer in bytes.
//
// Returns
// Required buffer size for AVCDecoderConfigurationRecord when converted
// to bytestream format, or 0 if could not determine the configuration
// from the input buffer.
uint32 ParseConfigurationAndCalculateSize(const uint8* configuration_record,
uint32 configuration_record_size);
// Calculates needed buffer size for the bitstream converted into bytestream.
// Lightweight implementation that does not do the actual conversion.
//
// Parameters
// configuration_record
// Pointer to buffer containing AVCDecoderConfigurationRecord.
// configuration_record_size
// Size of the buffer in bytes.
//
// Returns
// Required buffer size for the input NAL unit buffer when converted
// to bytestream format, or 0 if could not determine the configuration
// from the input buffer.
uint32 CalculateNeededOutputBufferSize(const uint8* input,
uint32 input_size) const;
// ConvertParameterSetsToByteStream converts the
// AVCDecoderConfigurationRecord from the MP4 headers to bytestream format.
// Client is responsible for making sure the output buffer is large enough
// to hold the output data. Client can precalculate the needed output buffer
// size by using ParseConfigurationAndCalculateSize.
//
// In case of failed conversion object H264BitstreamConverter may have written
// some bytes to buffer pointed by pinput but user should ignore those bytes.
// None of the outputs should be considered valid.
//
// Parameters
// pinput
// Pointer to buffer containing AVCDecoderConfigurationRecord.
// input_size
// Size of the buffer in bytes.
// poutput
// Pointer to buffer where the output should be written to.
// poutput_size (i/o)
// Pointer to the size of the output buffer. Will contain the number of
// bytes written to output after successful call.
//
// Returns
// true if successful conversion
// false if conversion not successful (poutput_size will hold the amount
// of converted data)
bool ConvertAVCDecoderConfigurationRecordToByteStream(const uint8* input,
uint32 input_size,
uint8* output,
uint32* output_size);
// ConvertNalUnitStreamToByteStream converts the NAL unit from MP4 format
// to bytestream format. Client is responsible for making sure the output
// buffer is large enough to hold the output data. Client can precalculate the
// needed output buffer size by using CalculateNeededOutputBufferSize.
//
// In case of failed conversion object H264BitstreamConverter may have written
// some bytes to buffer pointed by pinput but user should ignore those bytes.
// None of the outputs should be considered valid.
//
// Parameters
// pinput
// Pointer to buffer containing AVCDecoderConfigurationRecord.
// input_size
// Size of the buffer in bytes.
// poutput
// Pointer to buffer where the output should be written to.
// poutput_size (i/o)
// Pointer to the size of the output buffer. Will contain the number of
// bytes written to output after successful call.
//
// Returns
// true if successful conversion
// false if conversion not successful (poutput_size will hold the amount
// of converted data)
bool ConvertNalUnitStreamToByteStream(const uint8* input, uint32 input_size,
uint8* output, uint32* output_size);
private:
// Flag for indicating whether global parameter sets have been processed.
bool configuration_processed_;
// Flag for indicating whether next NAL unit starts new access unit.
bool first_nal_unit_in_access_unit_;
// Variable to hold interleaving field's length in bytes.
uint8 nal_unit_length_field_width_;
DISALLOW_COPY_AND_ASSIGN(H264BitstreamConverter);
};
} // namespace media
#endif // MEDIA_BASE_H264_BITSTREAM_CONVERTER_H_
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