static
TRANSPORTDEC_ERROR synchronization(
HANDLE_TRANSPORTDEC hTp,
INT *pHeaderBits
)
{
TRANSPORTDEC_ERROR err = TRANSPORTDEC_OK, errFirstFrame = TRANSPORTDEC_OK;
HANDLE_FDK_BITSTREAM hBs = &hTp->bitStream[0];
INT syncLayerFrameBits = 0; /* Length of sync layer frame (i.e. LOAS) */
INT rawDataBlockLength = 0, rawDataBlockLengthPrevious;
INT totalBits;
INT headerBits = 0, headerBitsFirstFrame = 0, headerBitsPrevious;
INT numFramesTraversed = 0, fTraverseMoreFrames, fConfigFound = 0, startPos, startPosFirstFrame = -1;
INT numRawDataBlocksFirstFrame = 0, numRawDataBlocksPrevious, globalFramePosFirstFrame = 0, rawDataBlockLengthFirstFrame = 0;
INT ignoreBufferFullness = hTp->flags & (TPDEC_IGNORE_BUFFERFULLNESS|TPDEC_SYNCOK);
/* Synch parameters */
INT syncLength; /* Length of sync word in bits */
UINT syncWord; /* Sync word to be found */
UINT syncMask; /* Mask for sync word (for adding one bit, so comprising one bit less) */
C_ALLOC_SCRATCH_START(contextFirstFrame, transportdec_parser_t, 1);
totalBits = (INT)FDKgetValidBits(hBs);
if (totalBits <= 0) {
/* Return sync error, because this happens only in case of severly damaged bit streams.
Returning TRANSPORTDEC_NOT_ENOUGH_BITS here is very dangerous. */
/* numberOfRawDataBlocks must be always reset in case of sync errors. */
hTp->numberOfRawDataBlocks = 0;
goto bail;
}
fTraverseMoreFrames = (hTp->flags & (TPDEC_MINIMIZE_DELAY|TPDEC_EARLY_CONFIG)) && ! (hTp->flags & TPDEC_SYNCOK);
/* Set transport specific sync parameters */
switch (hTp->transportFmt) {
case TT_MP4_ADTS:
syncWord = ADTS_SYNCWORD;
syncLength = ADTS_SYNCLENGTH;
break;
case TT_MP4_LOAS:
syncWord = 0x2B7;
syncLength = 11;
break;
default:
syncWord = 0;
syncLength = 0;
break;
}
syncMask = (1<<syncLength)-1;
do {
INT bitsAvail = 0; /* Bits available in bitstream buffer */
INT checkLengthBits; /* Helper to check remaining bits and buffer boundaries */
UINT synch; /* Current sync word read from bitstream */
headerBitsPrevious = headerBits;
bitsAvail = (INT)FDKgetValidBits(hBs);
if (hTp->numberOfRawDataBlocks == 0) {
/* search synchword */
FDK_ASSERT( (bitsAvail % TPDEC_SYNCSKIP) == 0);
if ((bitsAvail-syncLength) < TPDEC_SYNCSKIP) {
err = TRANSPORTDEC_NOT_ENOUGH_BITS;
headerBits = 0;
} else {
synch = FDKreadBits(hBs, syncLength);
if ( !(hTp->flags & TPDEC_SYNCOK) ) {
for (; (bitsAvail-syncLength) >= TPDEC_SYNCSKIP; bitsAvail-=TPDEC_SYNCSKIP) {
if (synch == syncWord) {
break;
}
synch = ((synch << TPDEC_SYNCSKIP) & syncMask) | FDKreadBits(hBs, TPDEC_SYNCSKIP);
}
}
if (synch != syncWord) {
/* No correct syncword found. */
err = TRANSPORTDEC_SYNC_ERROR;
} else {
err = TRANSPORTDEC_OK;
}
headerBits = syncLength;
}
} else {
headerBits = 0;
}
/* Save previous raw data block data */
rawDataBlockLengthPrevious = rawDataBlockLength;
numRawDataBlocksPrevious = hTp->numberOfRawDataBlocks;
/* Parse transport header (raw data block granularity) */
startPos = FDKgetValidBits(hBs);
if (err == TRANSPORTDEC_OK )
{
switch (hTp->transportFmt) {
case TT_MP4_ADTS:
if (hTp->numberOfRawDataBlocks <= 0)
{
int errC;
/* Parse ADTS header */
err = adtsRead_DecodeHeader( &hTp->parser.adts, &hTp->asc[0], hBs, ignoreBufferFullness );
if (err != TRANSPORTDEC_OK) {
if (err != TRANSPORTDEC_NOT_ENOUGH_BITS) {
err = TRANSPORTDEC_SYNC_ERROR;
}
} else {
errC = hTp->callbacks.cbUpdateConfig(hTp->callbacks.cbUpdateConfigData, &hTp->asc[0]);
if (errC != 0) {
err = TRANSPORTDEC_SYNC_ERROR;
} else {
hTp->numberOfRawDataBlocks = hTp->parser.adts.bs.num_raw_blocks+1;
/* CAUTION: The PCE (if available) is declared to be a part of the header! */
hTp->globalFramePos = FDKgetValidBits(hBs) + hTp->parser.adts.bs.num_pce_bits;
}
}
}
else {
/* Reset CRC because the next bits are the beginning of a raw_data_block() */
FDKcrcReset(&hTp->parser.adts.crcInfo);
hTp->globalFramePos = FDKgetValidBits(hBs);
}
if (err == TRANSPORTDEC_OK) {
hTp->numberOfRawDataBlocks--;
rawDataBlockLength = adtsRead_GetRawDataBlockLength(&hTp->parser.adts, (hTp->parser.adts.bs.num_raw_blocks-hTp->numberOfRawDataBlocks));
syncLayerFrameBits = (hTp->parser.adts.bs.frame_length<<3) - (startPos - FDKgetValidBits(hBs)) - syncLength;
if (syncLayerFrameBits <= 0) {
err = TRANSPORTDEC_SYNC_ERROR;
}
} else {
hTp->numberOfRawDataBlocks = 0;
}
break;
case TT_MP4_LOAS:
if (hTp->numberOfRawDataBlocks <= 0)
{
syncLayerFrameBits = FDKreadBits(hBs, 13);
hTp->parser.latm.m_audioMuxLengthBytes = syncLayerFrameBits;
syncLayerFrameBits <<= 3;
}
case TT_MP4_LATM_MCP1:
case TT_MP4_LATM_MCP0:
if (hTp->numberOfRawDataBlocks <= 0)
{
hTp->globalFramePos = FDKgetValidBits(hBs);
err = CLatmDemux_Read(
hBs,
&hTp->parser.latm,
hTp->transportFmt,
&hTp->callbacks,
hTp->asc,
ignoreBufferFullness);
if (err != TRANSPORTDEC_OK) {
if (err != TRANSPORTDEC_NOT_ENOUGH_BITS) {
err = TRANSPORTDEC_SYNC_ERROR;
}
} else {
hTp->numberOfRawDataBlocks = CLatmDemux_GetNrOfSubFrames(&hTp->parser.latm);
syncLayerFrameBits -= startPos - FDKgetValidBits(hBs) - (13);
}
} else {
err = CLatmDemux_ReadPayloadLengthInfo(hBs, &hTp->parser.latm);
if (err != TRANSPORTDEC_OK) {
err = TRANSPORTDEC_SYNC_ERROR;
}
}
if (err == TRANSPORTDEC_OK) {
rawDataBlockLength = CLatmDemux_GetFrameLengthInBits(&hTp->parser.latm);
hTp->numberOfRawDataBlocks--;
} else {
hTp->numberOfRawDataBlocks = 0;
}
break;
default:
{
syncLayerFrameBits = 0;
}
break;
}
}
headerBits += startPos - (INT)FDKgetValidBits(hBs);
bitsAvail -= headerBits;
checkLengthBits = syncLayerFrameBits;
/* Check if the whole frame would fit the bitstream buffer */
if (err == TRANSPORTDEC_OK) {
if ( (checkLengthBits+headerBits) > ((TRANSPORTDEC_INBUF_SIZE<<3)-7) ) {
/* We assume that the size of the transport bit buffer has been
chosen to meet all system requirements, thus this condition
is considered a synchronisation error. */
err = TRANSPORTDEC_SYNC_ERROR;
} else {
if ( bitsAvail < checkLengthBits ) {
err = TRANSPORTDEC_NOT_ENOUGH_BITS;
}
}
}
if (err == TRANSPORTDEC_NOT_ENOUGH_BITS) {
break;
}
if (err == TRANSPORTDEC_SYNC_ERROR) {
int bits;
/* Enforce re-sync of transport headers. */
hTp->numberOfRawDataBlocks = 0;
/* Ensure that the bit amount lands and a multiple of TPDEC_SYNCSKIP */
bits = (bitsAvail + headerBits) % TPDEC_SYNCSKIP;
/* Rewind - TPDEC_SYNCSKIP, in order to look for a synch one bit ahead next time. */
FDKpushBiDirectional(hBs, -(headerBits - TPDEC_SYNCSKIP) + bits);
bitsAvail += headerBits - TPDEC_SYNCSKIP - bits;
headerBits = 0;
}
/* Frame traversal */
if ( fTraverseMoreFrames )
{
/* Save parser context for early config discovery "rewind all frames" */
if ( (hTp->flags & TPDEC_EARLY_CONFIG) && !(hTp->flags & TPDEC_MINIMIZE_DELAY))
{
/* ignore buffer fullness if just traversing additional frames for ECD */
ignoreBufferFullness = 1;
/* Save context in order to return later */
if ( err == TRANSPORTDEC_OK && startPosFirstFrame == -1 ) {
startPosFirstFrame = FDKgetValidBits(hBs);
numRawDataBlocksFirstFrame = hTp->numberOfRawDataBlocks;
globalFramePosFirstFrame = hTp->globalFramePos;
rawDataBlockLengthFirstFrame = rawDataBlockLength;
headerBitsFirstFrame = headerBits;
errFirstFrame = err;
FDKmemcpy(contextFirstFrame, &hTp->parser, sizeof(transportdec_parser_t));
}
/* Break when config was found or it is not possible anymore to find a config */
if (startPosFirstFrame != -1 && (fConfigFound || err != TRANSPORTDEC_OK)) {
break;
}
}
if (err == TRANSPORTDEC_OK) {
FDKpushFor(hBs, rawDataBlockLength);
bitsAvail -= rawDataBlockLength;
numFramesTraversed++;
/* Ignore error here itentionally. */
transportDec_AdjustEndOfAccessUnit(hTp);
}
}
} while ( fTraverseMoreFrames || (err == TRANSPORTDEC_SYNC_ERROR && !(hTp->flags & TPDEC_SYNCOK)));
/* Restore context in case of ECD frame traversal */
if ( startPosFirstFrame != -1 && (fConfigFound || err != TRANSPORTDEC_OK) ) {
FDKpushBiDirectional(hBs, FDKgetValidBits(hBs) - startPosFirstFrame);
FDKmemcpy(&hTp->parser, contextFirstFrame, sizeof(transportdec_parser_t));
hTp->numberOfRawDataBlocks = numRawDataBlocksFirstFrame;
hTp->globalFramePos = globalFramePosFirstFrame;
rawDataBlockLength = rawDataBlockLengthFirstFrame;
headerBits = headerBitsFirstFrame;
err = errFirstFrame;
numFramesTraversed = 0;
}
/* Additional burst data mode buffer fullness check. */
if ( !(hTp->flags & (TPDEC_IGNORE_BUFFERFULLNESS|TPDEC_SYNCOK)) && err == TRANSPORTDEC_OK) {
err = additionalHoldOffNeeded(hTp, transportDec_GetBufferFullness(hTp), FDKgetValidBits(hBs) - syncLayerFrameBits);
if (err == TRANSPORTDEC_NOT_ENOUGH_BITS) {
hTp->holdOffFrames++;
}
}
/* Rewind for retry because of not enough bits */
if (err == TRANSPORTDEC_NOT_ENOUGH_BITS) {
FDKpushBack(hBs, headerBits);
headerBits = 0;
}
else {
/* reset hold off frame counter */
hTp->holdOffFrames = 0;
}
/* Return to last good frame in case of frame traversal but not ECD. */
if (numFramesTraversed > 0) {
FDKpushBack(hBs, rawDataBlockLengthPrevious);
if (err != TRANSPORTDEC_OK) {
hTp->numberOfRawDataBlocks = numRawDataBlocksPrevious;
headerBits = headerBitsPrevious;
}
err = TRANSPORTDEC_OK;
}
bail:
hTp->auLength[0] = rawDataBlockLength;
if (err == TRANSPORTDEC_OK) {
hTp->flags |= TPDEC_SYNCOK;
}
if (pHeaderBits != NULL) {
*pHeaderBits = headerBits;
}
if (err == TRANSPORTDEC_SYNC_ERROR) {
hTp->flags &= ~TPDEC_SYNCOK;
}
C_ALLOC_SCRATCH_END(contextFirstFrame, transportdec_parser_t, 1);
return err;
}
static TRANSPORTDEC_ERROR transportDec_readHeader(
HANDLE_TRANSPORTDEC hTp,
HANDLE_FDK_BITSTREAM hBs,
int syncLength,
int ignoreBufferFullness,
int *pRawDataBlockLength,
int *pfTraverseMoreFrames,
int *pSyncLayerFrameBits,
int *pfConfigFound,
int *pHeaderBits
)
{
TRANSPORTDEC_ERROR err = TRANSPORTDEC_OK;
int rawDataBlockLength = *pRawDataBlockLength;
int fTraverseMoreFrames = (pfTraverseMoreFrames != NULL) ? *pfTraverseMoreFrames : 0;
int syncLayerFrameBits = (pSyncLayerFrameBits != NULL) ? *pSyncLayerFrameBits : 0;
int fConfigFound = (pfConfigFound != NULL) ? *pfConfigFound : 0;
int startPos;
startPos = FDKgetValidBits(hBs);
switch (hTp->transportFmt) {
case TT_MP4_ADTS:
if (hTp->numberOfRawDataBlocks <= 0)
{
int errC;
hTp->globalFramePos = FDKgetValidBits(hBs);
/* Parse ADTS header */
err = adtsRead_DecodeHeader( &hTp->parser.adts, &hTp->asc[0], hBs, ignoreBufferFullness );
if (err != TRANSPORTDEC_OK) {
if (err != TRANSPORTDEC_NOT_ENOUGH_BITS) {
err = TRANSPORTDEC_SYNC_ERROR;
}
} else {
errC = hTp->callbacks.cbUpdateConfig(hTp->callbacks.cbUpdateConfigData, &hTp->asc[0]);
if (errC != 0) {
if (errC == TRANSPORTDEC_NEED_TO_RESTART) {
err = TRANSPORTDEC_NEED_TO_RESTART;
goto bail;
} else {
err = TRANSPORTDEC_SYNC_ERROR;
}
} else {
fConfigFound = 1;
hTp->numberOfRawDataBlocks = hTp->parser.adts.bs.num_raw_blocks+1;
}
}
}
else {
/* Reset CRC because the next bits are the beginning of a raw_data_block() */
FDKcrcReset(&hTp->parser.adts.crcInfo);
hTp->parser.adts.bs.num_pce_bits = 0;
}
if (err == TRANSPORTDEC_OK) {
hTp->numberOfRawDataBlocks--;
rawDataBlockLength = adtsRead_GetRawDataBlockLength(&hTp->parser.adts, (hTp->parser.adts.bs.num_raw_blocks-hTp->numberOfRawDataBlocks));
if (rawDataBlockLength <= 0) {
/* No further frame traversal possible. */
fTraverseMoreFrames = 0;
}
syncLayerFrameBits = (hTp->parser.adts.bs.frame_length<<3) - (startPos - FDKgetValidBits(hBs)) - syncLength;
if (syncLayerFrameBits <= 0) {
err = TRANSPORTDEC_SYNC_ERROR;
}
} else {
hTp->numberOfRawDataBlocks = 0;
}
break;
case TT_MP4_LOAS:
if (hTp->numberOfRawDataBlocks <= 0)
{
syncLayerFrameBits = FDKreadBits(hBs, 13);
hTp->parser.latm.m_audioMuxLengthBytes = syncLayerFrameBits;
syncLayerFrameBits <<= 3;
}
case TT_MP4_LATM_MCP1:
case TT_MP4_LATM_MCP0:
if (hTp->numberOfRawDataBlocks <= 0)
{
hTp->globalFramePos = FDKgetValidBits(hBs);
err = CLatmDemux_Read(
hBs,
&hTp->parser.latm,
hTp->transportFmt,
&hTp->callbacks,
hTp->asc,
&fConfigFound,
ignoreBufferFullness);
if (err != TRANSPORTDEC_OK) {
if (err != TRANSPORTDEC_NOT_ENOUGH_BITS) {
err = TRANSPORTDEC_SYNC_ERROR;
}
} else {
hTp->numberOfRawDataBlocks = CLatmDemux_GetNrOfSubFrames(&hTp->parser.latm);
if (hTp->transportFmt == TT_MP4_LOAS) {
syncLayerFrameBits -= startPos - FDKgetValidBits(hBs) - (13);
}
}
} else {
err = CLatmDemux_ReadPayloadLengthInfo(hBs, &hTp->parser.latm);
if (err != TRANSPORTDEC_OK) {
err = TRANSPORTDEC_SYNC_ERROR;
}
}
if (err == TRANSPORTDEC_OK) {
rawDataBlockLength = CLatmDemux_GetFrameLengthInBits(&hTp->parser.latm);
hTp->numberOfRawDataBlocks--;
} else {
hTp->numberOfRawDataBlocks = 0;
}
break;
default:
{
syncLayerFrameBits = 0;
}
break;
}
bail:
*pRawDataBlockLength = rawDataBlockLength;
if (pHeaderBits != NULL) {
*pHeaderBits += startPos - (INT)FDKgetValidBits(hBs);
}
if (pfConfigFound != NULL) {
*pfConfigFound = fConfigFound;
}
if (pfTraverseMoreFrames != NULL) {
*pfTraverseMoreFrames = fTraverseMoreFrames;
}
if (pSyncLayerFrameBits != NULL) {
*pSyncLayerFrameBits = syncLayerFrameBits;
}
if (pfConfigFound != NULL) {
*pfConfigFound = fConfigFound;
}
return err;
}
