ref: c44c0332357abb38513127baeb4303c2c4663e44
dir: /common/mp4av/adts.cpp/
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is MPEG4IP.
*
* The Initial Developer of the Original Code is Cisco Systems Inc.
* Portions created by Cisco Systems Inc. are
* Copyright (C) Cisco Systems Inc. 2000-2002. All Rights Reserved.
*
* Contributor(s):
* Dave Mackie [email protected]
*/
/*
* Notes:
* - file formatted with tabstops == 4 spaces
*/
#include <mp4av_common.h>
/*
* ADTS Header:
* MPEG-2 version 56 bits (byte aligned)
* MPEG-4 version 58 bits (not byte aligned)
*
* syncword 12 bits
* id 1 bit
* layer 2 bits
* protection_absent 1 bit
* profile 2 bits
* sampling_frequency_index 4 bits
* private 1 bit
* channel_configuraton 3 bits
* original 1 bit
* home 1 bit
* emphasis 2 bits
* copyright_id 1 bit
* copyright_id_start 1 bit
* aac_frame_length 13 bits
* adts_buffer_fullness 11 bits
* num_raw_data_blocks 2 bits
*
* if (protection_absent == 0)
* crc_check 16 bits
*/
u_int32_t AdtsSamplingRates[NUM_ADTS_SAMPLING_RATES] = {
96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050,
16000, 12000, 11025, 8000, 7350, 0, 0, 0
};
/*
* compute ADTS frame size
*/
extern "C" u_int16_t MP4AV_AdtsGetFrameSize(u_int8_t* pHdr)
{
/* extract the necessary fields from the header */
u_int8_t isMpeg4 = !(pHdr[1] & 0x08);
u_int16_t frameLength;
if (isMpeg4) {
frameLength = (((u_int16_t)pHdr[4]) << 5) | (pHdr[5] >> 3);
} else { /* MPEG-2 */
frameLength = (((u_int16_t)(pHdr[3] & 0x3)) << 11)
| (((u_int16_t)pHdr[4]) << 3) | (pHdr[5] >> 5);
}
return frameLength;
}
/*
* Compute length of ADTS header in bits
*/
extern "C" u_int16_t MP4AV_AdtsGetHeaderBitSize(u_int8_t* pHdr)
{
u_int8_t isMpeg4 = !(pHdr[1] & 0x08);
u_int8_t hasCrc = !(pHdr[1] & 0x01);
u_int16_t hdrSize;
if (isMpeg4) {
hdrSize = 58;
} else {
hdrSize = 56;
}
if (hasCrc) {
hdrSize += 16;
}
return hdrSize;
}
extern "C" u_int16_t MP4AV_AdtsGetHeaderByteSize(u_int8_t* pHdr)
{
return (MP4AV_AdtsGetHeaderBitSize(pHdr) + 7) / 8;
}
extern "C" u_int8_t MP4AV_AdtsGetVersion(u_int8_t* pHdr)
{
return (pHdr[1] & 0x08) >> 3;
}
extern "C" u_int8_t MP4AV_AdtsGetProfile(u_int8_t* pHdr)
{
return (pHdr[2] & 0xc0) >> 6;
}
extern "C" u_int8_t MP4AV_AdtsGetSamplingRateIndex(u_int8_t* pHdr)
{
return (pHdr[2] & 0x3c) >> 2;
}
extern "C" u_int8_t MP4AV_AdtsFindSamplingRateIndex(u_int32_t samplingRate)
{
for (u_int8_t i = 0; i < NUM_ADTS_SAMPLING_RATES; i++) {
if (samplingRate == AdtsSamplingRates[i]) {
return i;
}
}
return NUM_ADTS_SAMPLING_RATES - 1;
}
extern "C" u_int32_t MP4AV_AdtsGetSamplingRate(u_int8_t* pHdr)
{
return AdtsSamplingRates[MP4AV_AdtsGetSamplingRateIndex(pHdr)];
}
extern "C" u_int8_t MP4AV_AdtsGetChannels(u_int8_t* pHdr)
{
return ((pHdr[2] & 0x1) << 2) | ((pHdr[3] & 0xc0) >> 6);
}
extern "C" bool MP4AV_AdtsMakeFrameFromMp4Sample(
MP4FileHandle mp4File,
MP4TrackId trackId,
MP4SampleId sampleId,
u_int8_t** ppAdtsData,
u_int32_t* pAdtsDataLength)
{
static MP4FileHandle lastMp4File = MP4_INVALID_FILE_HANDLE;
static MP4TrackId lastMp4TrackId = MP4_INVALID_TRACK_ID;
static bool isMpeg2;
static u_int8_t profile;
static u_int32_t samplingFrequency;
static u_int8_t channels;
if (mp4File != lastMp4File || trackId != lastMp4TrackId) {
// changed cached file and track info
lastMp4File = mp4File;
lastMp4TrackId = trackId;
u_int8_t audioType = MP4GetTrackAudioType(mp4File, trackId);
if (MP4_IS_MPEG2_AAC_AUDIO_TYPE(audioType)) {
isMpeg2 = true;
profile = audioType - MP4_MPEG2_AAC_MAIN_AUDIO_TYPE;
} else if (audioType == MP4_MPEG4_AUDIO_TYPE) {
isMpeg2 = false;
profile = MP4GetTrackAudioMpeg4Type(mp4File, trackId) - 1;
} else {
lastMp4File = MP4_INVALID_FILE_HANDLE;
lastMp4TrackId = MP4_INVALID_TRACK_ID;
return false;
}
u_int8_t* pConfig = NULL;
u_int32_t configLength;
MP4GetTrackESConfiguration(
mp4File,
trackId,
&pConfig,
&configLength);
if (pConfig == NULL || configLength < 2) {
lastMp4File = MP4_INVALID_FILE_HANDLE;
lastMp4TrackId = MP4_INVALID_TRACK_ID;
return false;
}
samplingFrequency = MP4AV_AacConfigGetSamplingRate(pConfig);
channels = MP4AV_AacConfigGetChannels(pConfig);
}
bool rc;
u_int8_t* pSample = NULL;
u_int32_t sampleSize = 0;
rc = MP4ReadSample(
mp4File,
trackId,
sampleId,
&pSample,
&sampleSize);
if (!rc) {
return false;
}
rc = MP4AV_AdtsMakeFrame(
pSample,
sampleSize,
isMpeg2,
profile,
samplingFrequency,
channels,
ppAdtsData,
pAdtsDataLength);
free(pSample);
return rc;
}
extern "C" bool MP4AV_AdtsMakeFrame(
u_int8_t* pData,
u_int16_t dataLength,
bool isMpeg2,
u_int8_t profile,
u_int32_t samplingFrequency,
u_int8_t channels,
u_int8_t** ppAdtsData,
u_int32_t* pAdtsDataLength)
{
*pAdtsDataLength = (isMpeg2 ? 7 : 8) + dataLength;
CMemoryBitstream adts;
try {
adts.AllocBytes(*pAdtsDataLength);
*ppAdtsData = adts.GetBuffer();
// build adts header
adts.PutBits(0xFFF, 12); // syncword
adts.PutBits(isMpeg2, 1); // id
adts.PutBits(0, 2); // layer
adts.PutBits(1, 1); // protection_absent
adts.PutBits(profile, 2); // profile
adts.PutBits(
MP4AV_AdtsFindSamplingRateIndex(samplingFrequency),
4); // sampling_frequency_index
adts.PutBits(0, 1); // private
adts.PutBits(channels, 3); // channel_configuration
adts.PutBits(0, 1); // original
adts.PutBits(0, 1); // home
if (!isMpeg2) {
adts.PutBits(0, 2); // emphasis
}
adts.PutBits(0, 1); // copyright_id
adts.PutBits(0, 1); // copyright_id_start
adts.PutBits(*pAdtsDataLength, 13); // aac_frame_length
adts.PutBits(0x7FF, 11); // adts_buffer_fullness
adts.PutBits(0, 2); // num_raw_data_blocks
// copy audio frame data
adts.PutBytes(pData, dataLength);
}
catch (int e) {
return false;
}
return true;
}