stbl_read.c

一个用于智能手机的多媒体库适合S60 WinCE的跨平台开发库

	GF_StscEntry *nextEnt;
	GF_ChunkOffsetBox *stco;
	GF_ChunkLargeOffsetBox *co64;
	u32 ghostNum = 1;

	if (!ent->nextChunk) {
		if (EntryIndex+1 == count) {
			//not specified in the spec, what if the last sample to chunk is no written?
			if (stbl->ChunkOffset->type == GF_ISOM_BOX_TYPE_STCO) {
				stco = (GF_ChunkOffsetBox *)stbl->ChunkOffset;
				ghostNum = (stco->entryCount > ent->firstChunk) ? (1 + stco->entryCount - ent->firstChunk) : 1;
			} else {
				co64 = (GF_ChunkLargeOffsetBox *)stbl->ChunkOffset;
				ghostNum = (co64->entryCount > ent->firstChunk) ? (1 + co64->entryCount - ent->firstChunk) : 1;
			}
		} else {
			//this is an unknown case due to edit mode...
			nextEnt = (GF_StscEntry*)gf_list_get(stbl->SampleToChunk->entryList, EntryIndex+1);
			ghostNum = nextEnt->firstChunk - ent->firstChunk;
		}
	} else {
		ghostNum = (ent->nextChunk > ent->firstChunk) ? (ent->nextChunk - ent->firstChunk) : 1;
	}
	stbl->SampleToChunk->ghostNumber = ghostNum;
}

//Get the offset, descIndex and chunkNumber of a sample...
GF_Err stbl_GetSampleInfos(GF_SampleTableBox *stbl, u32 sampleNumber, u64 *offset, u32 *chunkNumber, u32 *descIndex, u8 *isEdited)
{
	GF_Err e;
	u32 i, j, k, offsetInChunk, size, count;
	GF_ChunkOffsetBox *stco;
	GF_ChunkLargeOffsetBox *co64;
	GF_StscEntry *ent;

	(*offset) = 0;
	(*chunkNumber) = (*descIndex) = 0;
	(*isEdited) = 0;
	if (!stbl || !sampleNumber) return GF_BAD_PARAM;

	count = gf_list_count(stbl->SampleToChunk->entryList);
	if (count==stbl->SampleSize->sampleCount) {
		ent = (GF_StscEntry *)gf_list_get(stbl->SampleToChunk->entryList, sampleNumber-1);
		if (!ent) return GF_BAD_PARAM;
		(*descIndex) = ent->sampleDescriptionIndex;
		(*chunkNumber) = sampleNumber;
		(*isEdited) = ent->isEdited;
		if ( stbl->ChunkOffset->type == GF_ISOM_BOX_TYPE_STCO) {
			stco = (GF_ChunkOffsetBox *)stbl->ChunkOffset;
			(*offset) = (u64) stco->offsets[sampleNumber - 1];
		} else {
			co64 = (GF_ChunkLargeOffsetBox *)stbl->ChunkOffset;
			(*offset) = co64->offsets[sampleNumber - 1];
		}
		return GF_OK;
	}

	//check our cache
	if (stbl->SampleToChunk->firstSampleInCurrentChunk &&
		(stbl->SampleToChunk->firstSampleInCurrentChunk < sampleNumber)) {
		
		i = stbl->SampleToChunk->currentIndex;
//		ent = gf_list_get(stbl->SampleToChunk->entryList, i);
		ent = stbl->SampleToChunk->currentEntry;
		GetGhostNum(ent, i, count, stbl);
		k = stbl->SampleToChunk->currentChunk;
	} else {
		i = 0;
		stbl->SampleToChunk->currentIndex = 0;
		stbl->SampleToChunk->currentChunk = 1;
		stbl->SampleToChunk->firstSampleInCurrentChunk = 1;
		ent = (GF_StscEntry*)gf_list_get(stbl->SampleToChunk->entryList, 0);
		stbl->SampleToChunk->currentEntry = ent;
		GetGhostNum(ent, 0, count, stbl);
		k = stbl->SampleToChunk->currentChunk;
	}

	//first get the chunk
	for (; i < count; i++) {
		//browse from the current chunk we're browsing from index 1
		for (; k <= stbl->SampleToChunk->ghostNumber; k++) {
			//browse all the samples in this chunk
			for (j = 0; j < ent->samplesPerChunk; j++) {
				//ok, this is our sample
				if (stbl->SampleToChunk->firstSampleInCurrentChunk + j == sampleNumber ) 
					goto sample_found;
			}
			//nope, get to next chunk
			stbl->SampleToChunk->firstSampleInCurrentChunk += ent->samplesPerChunk;
			stbl->SampleToChunk->currentChunk ++;
		}
		//not in this entry, get the next entry if not the last one
		if (i+1 != count) {
			ent = (GF_StscEntry*)gf_list_get(stbl->SampleToChunk->entryList, i+1);
			//update the GhostNumber
			GetGhostNum(ent, i+1, count, stbl);
			//update the entry in our cache
			stbl->SampleToChunk->currentEntry = ent;
			stbl->SampleToChunk->currentIndex = i+1;
			stbl->SampleToChunk->currentChunk = 1;
			k = 1;
		}
	}
	//if we get here, gasp, the sample was not found
	return GF_ISOM_INVALID_FILE;

sample_found:

	(*descIndex) = ent->sampleDescriptionIndex;
	(*chunkNumber) = ent->firstChunk + stbl->SampleToChunk->currentChunk - 1;
	(*isEdited) = ent->isEdited;

	//ok, get the size of all the previous sample
	offsetInChunk = 0;
	//warning, firstSampleInChunk is at least 1 - not 0
	for (i = stbl->SampleToChunk->firstSampleInCurrentChunk; i < sampleNumber; i++) {
		e = stbl_GetSampleSize(stbl->SampleSize, i, &size);
		if (e) return e;
		offsetInChunk += size;
	}
	//OK, that's the size of our offset in the chunk
	//now get the chunk
	if ( stbl->ChunkOffset->type == GF_ISOM_BOX_TYPE_STCO) {
		stco = (GF_ChunkOffsetBox *)stbl->ChunkOffset;
		if (stco->entryCount < (*chunkNumber) ) return GF_ISOM_INVALID_FILE;
		(*offset) = (u64) stco->offsets[(*chunkNumber) - 1] + (u64) offsetInChunk;
	} else {
		co64 = (GF_ChunkLargeOffsetBox *)stbl->ChunkOffset;
		if (co64->entryCount < (*chunkNumber) ) return GF_ISOM_INVALID_FILE;
		(*offset) = co64->offsets[(*chunkNumber) - 1] + (u64) offsetInChunk;
	}
	return GF_OK;
}


GF_Err stbl_GetSampleShadow(GF_ShadowSyncBox *stsh, u32 *sampleNumber, u32 *syncNum)
{
	u32 i, count;
	GF_StshEntry *ent;

	if (stsh->r_LastFoundSample && (stsh->r_LastFoundSample <= *sampleNumber)) {
		i = stsh->r_LastEntryIndex;
	} else {
		i = 0;
		stsh->r_LastFoundSample = 1;
	}

	ent = NULL;
	(*syncNum) = 0;

	count = gf_list_count(stsh->entries);
	for (; i<count; i++) {
		ent = (GF_StshEntry*)gf_list_get(stsh->entries, i);
		//we get the exact desired sample !
		if (ent->shadowedSampleNumber == *sampleNumber) {
			(*syncNum) = ent->syncSampleNumber;
			stsh->r_LastFoundSample = *sampleNumber;
			stsh->r_LastEntryIndex = i;
			return GF_OK;
		} else if (ent->shadowedSampleNumber > *sampleNumber) {
			//do we have an entry before ? If not, there is no shadowing available
			//for this sample
			if (!i) return GF_OK;
			//ok, indicate the previous ShadowedSample
			ent = (GF_StshEntry*)gf_list_get(stsh->entries, i-1);
			(*syncNum) = ent->syncSampleNumber;
			//change the sample number
			(*sampleNumber) = ent->shadowedSampleNumber;
			//reset the cache to the last ShadowedSample
			stsh->r_LastEntryIndex = i-1;
			stsh->r_LastFoundSample = ent->shadowedSampleNumber;
		}
	}
	stsh->r_LastEntryIndex = i-1;
	stsh->r_LastFoundSample = ent ? ent->shadowedSampleNumber : 0;
	return GF_OK;
}



GF_Err stbl_GetPaddingBits(GF_PaddingBitsBox *padb, u32 SampleNumber, u8 *PadBits)
{
	if (!PadBits) return GF_BAD_PARAM;
	*PadBits = 0;
	if (!padb || !padb->padbits) return GF_OK;
	//the spec says "should" not shall. return 0 padding 
	if (padb->SampleCount < SampleNumber) return GF_OK;
	*PadBits = padb->padbits[SampleNumber-1];
	return GF_OK;
}

//Set the RAP flag of a sample
GF_Err stbl_GetSampleDepType(GF_SampleDependencyTypeBox *sdep, u32 SampleNumber, u32 *dependsOn, u32 *dependedOn, u32 *redundant)
{
	u8 flag;

	assert(dependsOn && dependedOn && redundant);
	*dependsOn = *dependedOn = *redundant = 0;

	if (SampleNumber > sdep->sampleCount) return GF_BAD_PARAM;
	flag = sdep->sample_info[SampleNumber-1];
	*dependsOn = (flag >> 4) & 3;
	*dependedOn = (flag >> 2) & 3;
	*redundant = (flag) & 3;
	return GF_OK;
}

u32 stbl_GetSampleFragmentCount(GF_SampleFragmentBox *stsf, u32 sampleNumber)
{
	GF_StsfEntry *ent;
	u32 i, count;
	if (!stsf) return 0;

	//check cache
	if (!stsf->r_currentEntry || (stsf->r_currentEntry->SampleNumber < sampleNumber)) {
		stsf->r_currentEntry = NULL;
		stsf->r_currentEntryIndex = 0;
	}
	i = stsf->r_currentEntryIndex;
	
	count = gf_list_count(stsf->entryList);
	for (; i<count; i++) {
		ent = (GF_StsfEntry *)gf_list_get(stsf->entryList, i);
		if (ent->SampleNumber == sampleNumber) {
			stsf->r_currentEntry = ent;
			stsf->r_currentEntryIndex = i;
			return ent->fragmentCount;
		}
	}
	//not found
	return 0;
}

u32 stbl_GetSampleFragmentSize(GF_SampleFragmentBox *stsf, u32 sampleNumber, u32 FragmentIndex)
{
	GF_StsfEntry *ent;
	u32 i, count;
	if (!stsf || !FragmentIndex) return 0;

	//check cache
	if (!stsf->r_currentEntry || (stsf->r_currentEntry->SampleNumber < sampleNumber)) {
		stsf->r_currentEntry = NULL;
		stsf->r_currentEntryIndex = 0;
	}
	i = stsf->r_currentEntryIndex;
	count = gf_list_count(stsf->entryList);
	for (; i<count; i++) {
		ent = (GF_StsfEntry *)gf_list_get(stsf->entryList, i);
		if (ent->SampleNumber == sampleNumber) {
			stsf->r_currentEntry = ent;
			stsf->r_currentEntryIndex = i;
			if (FragmentIndex > ent->fragmentCount) return 0;
			return ent->fragmentSizes[FragmentIndex - 1];
		}
	}
	//not found
	return 0;
}