| /* |
| * Copyright (C) 2009 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /*------------------------------------------------------------------------------ |
| |
| Table of contents |
| |
| 1. Include headers |
| 2. External compiler flags |
| 3. Module defines |
| 4. Local function prototypes |
| 5. Functions |
| ExtractNalUnit |
| |
| ------------------------------------------------------------------------------*/ |
| |
| /*------------------------------------------------------------------------------ |
| 1. Include headers |
| ------------------------------------------------------------------------------*/ |
| |
| #include "h264bsd_byte_stream.h" |
| #include "h264bsd_util.h" |
| |
| /*------------------------------------------------------------------------------ |
| 2. External compiler flags |
| -------------------------------------------------------------------------------- |
| |
| -------------------------------------------------------------------------------- |
| 3. Module defines |
| ------------------------------------------------------------------------------*/ |
| |
| #define BYTE_STREAM_ERROR 0xFFFFFFFF |
| |
| /*------------------------------------------------------------------------------ |
| 4. Local function prototypes |
| ------------------------------------------------------------------------------*/ |
| |
| /*------------------------------------------------------------------------------ |
| |
| Function name: ExtractNalUnit |
| |
| Functional description: |
| Extracts one NAL unit from the byte stream buffer. Removes |
| emulation prevention bytes if present. The original stream buffer |
| is used directly and is therefore modified if emulation prevention |
| bytes are present in the stream. |
| |
| Stream buffer is assumed to contain either exactly one NAL unit |
| and nothing else, or one or more NAL units embedded in byte |
| stream format described in the Annex B of the standard. Function |
| detects which one is used based on the first bytes in the buffer. |
| |
| Inputs: |
| pByteStream pointer to byte stream buffer |
| len length of the stream buffer (in bytes) |
| |
| Outputs: |
| pStrmData stream information is stored here |
| readBytes number of bytes "consumed" from the stream buffer |
| |
| Returns: |
| HANTRO_OK success |
| HANTRO_NOK error in byte stream |
| |
| ------------------------------------------------------------------------------*/ |
| |
| u32 h264bsdExtractNalUnit(u8 *pByteStream, u32 len, strmData_t *pStrmData, |
| u32 *readBytes) |
| { |
| |
| /* Variables */ |
| |
| u32 i, tmp; |
| u32 byteCount,initByteCount; |
| u32 zeroCount; |
| u8 byte; |
| u32 hasEmulation = HANTRO_FALSE; |
| u32 invalidStream = HANTRO_FALSE; |
| u8 *readPtr, *writePtr; |
| |
| /* Code */ |
| |
| ASSERT(pByteStream); |
| ASSERT(len); |
| ASSERT(len < BYTE_STREAM_ERROR); |
| ASSERT(pStrmData); |
| |
| /* byte stream format if starts with 0x000001 or 0x000000 */ |
| if (len > 3 && pByteStream[0] == 0x00 && pByteStream[1] == 0x00 && |
| (pByteStream[2]&0xFE) == 0x00) |
| { |
| /* search for NAL unit start point, i.e. point after first start code |
| * prefix in the stream */ |
| zeroCount = byteCount = 2; |
| readPtr = pByteStream + 2; |
| /*lint -e(716) while(1) used consciously */ |
| while (1) |
| { |
| byte = *readPtr++; |
| byteCount++; |
| |
| if (byteCount == len) |
| { |
| /* no start code prefix found -> error */ |
| *readBytes = len; |
| return(HANTRO_NOK); |
| } |
| |
| if (!byte) |
| zeroCount++; |
| else if ((byte == 0x01) && (zeroCount >= 2)) |
| break; |
| else |
| zeroCount = 0; |
| } |
| |
| initByteCount = byteCount; |
| |
| /* determine size of the NAL unit. Search for next start code prefix |
| * or end of stream and ignore possible trailing zero bytes */ |
| zeroCount = 0; |
| /*lint -e(716) while(1) used consciously */ |
| while (1) |
| { |
| byte = *readPtr++; |
| byteCount++; |
| if (!byte) |
| zeroCount++; |
| |
| if ( (byte == 0x03) && (zeroCount == 2) ) |
| { |
| hasEmulation = HANTRO_TRUE; |
| } |
| |
| if ( (byte == 0x01) && (zeroCount >= 2 ) ) |
| { |
| pStrmData->strmBuffSize = |
| byteCount - initByteCount - zeroCount - 1; |
| zeroCount -= MIN(zeroCount, 3); |
| break; |
| } |
| else if (byte) |
| { |
| if (zeroCount >= 3) |
| invalidStream = HANTRO_TRUE; |
| zeroCount = 0; |
| } |
| |
| if (byteCount == len) |
| { |
| pStrmData->strmBuffSize = byteCount - initByteCount - zeroCount; |
| break; |
| } |
| |
| } |
| } |
| /* separate NAL units as input -> just set stream params */ |
| else |
| { |
| initByteCount = 0; |
| zeroCount = 0; |
| pStrmData->strmBuffSize = len; |
| hasEmulation = HANTRO_TRUE; |
| } |
| |
| pStrmData->pStrmBuffStart = pByteStream + initByteCount; |
| pStrmData->pStrmCurrPos = pStrmData->pStrmBuffStart; |
| pStrmData->bitPosInWord = 0; |
| pStrmData->strmBuffReadBits = 0; |
| |
| /* return number of bytes "consumed" */ |
| *readBytes = pStrmData->strmBuffSize + initByteCount + zeroCount; |
| |
| if (invalidStream) |
| { |
| return(HANTRO_NOK); |
| } |
| |
| /* remove emulation prevention bytes before rbsp processing */ |
| if (hasEmulation) |
| { |
| tmp = pStrmData->strmBuffSize; |
| readPtr = writePtr = pStrmData->pStrmBuffStart; |
| zeroCount = 0; |
| for (i = tmp; i--;) |
| { |
| if ((zeroCount == 2) && (*readPtr == 0x03)) |
| { |
| /* emulation prevention byte shall be followed by one of the |
| * following bytes: 0x00, 0x01, 0x02, 0x03. This implies that |
| * emulation prevention 0x03 byte shall not be the last byte |
| * of the stream. */ |
| if ( (i == 0) || (*(readPtr+1) > 0x03) ) |
| return(HANTRO_NOK); |
| |
| /* do not write emulation prevention byte */ |
| readPtr++; |
| zeroCount = 0; |
| } |
| else |
| { |
| /* NAL unit shall not contain byte sequences 0x000000, |
| * 0x000001 or 0x000002 */ |
| if ( (zeroCount == 2) && (*readPtr <= 0x02) ) |
| return(HANTRO_NOK); |
| |
| if (*readPtr == 0) |
| zeroCount++; |
| else |
| zeroCount = 0; |
| |
| *writePtr++ = *readPtr++; |
| } |
| } |
| |
| /* (readPtr - writePtr) indicates number of "removed" emulation |
| * prevention bytes -> subtract from stream buffer size */ |
| pStrmData->strmBuffSize -= (u32)(readPtr - writePtr); |
| } |
| |
| return(HANTRO_OK); |
| |
| } |
| |
