Retired Document
Important: This sample code may not represent best practices for current development. The project may use deprecated symbols and illustrate technologies and techniques that are no longer recommended.
Relevant replacement documents include:
PublicUtility/CAStreamBasicDescription.cpp
/* |
<codex> |
<abstract>CAStreamBasicDescription.h</abstract> |
<\codex> |
*/ |
#include "CAStreamBasicDescription.h" |
#include "CAMath.h" |
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__) |
#include <CoreFoundation/CFByteOrder.h> |
#else |
#include <CFByteOrder.h> |
#endif |
#pragma mark This file needs to compile on earlier versions of the OS, so please keep that in mind when editing it |
char *CAStringForOSType (OSType t, char *writeLocation) |
{ |
char *p = writeLocation; |
unsigned char str[4] = {0}, *q = str; |
*(UInt32 *)str = CFSwapInt32HostToBig(t); |
bool hasNonPrint = false; |
for (int i = 0; i < 4; ++i) { |
if (!(isprint(*q) && *q != '\\')) { |
hasNonPrint = true; |
break; |
} |
q++; |
} |
q = str; |
if (hasNonPrint) |
p += sprintf (p, "0x"); |
else |
*p++ = '\''; |
for (int i = 0; i < 4; ++i) { |
if (hasNonPrint) { |
p += sprintf(p, "%02X", *q++); |
} else { |
*p++ = *q++; |
} |
} |
if (!hasNonPrint) |
*p++ = '\''; |
*p = '\0'; |
return writeLocation; |
} |
const AudioStreamBasicDescription CAStreamBasicDescription::sEmpty = { 0.0, 0, 0, 0, 0, 0, 0, 0, 0 }; |
CAStreamBasicDescription::CAStreamBasicDescription() |
{ |
memset (this, 0, sizeof(AudioStreamBasicDescription)); |
} |
CAStreamBasicDescription::CAStreamBasicDescription(const AudioStreamBasicDescription &desc) |
{ |
SetFrom(desc); |
} |
CAStreamBasicDescription::CAStreamBasicDescription(double inSampleRate, UInt32 inFormatID, |
UInt32 inBytesPerPacket, UInt32 inFramesPerPacket, |
UInt32 inBytesPerFrame, UInt32 inChannelsPerFrame, |
UInt32 inBitsPerChannel, UInt32 inFormatFlags) |
{ |
mSampleRate = inSampleRate; |
mFormatID = inFormatID; |
mBytesPerPacket = inBytesPerPacket; |
mFramesPerPacket = inFramesPerPacket; |
mBytesPerFrame = inBytesPerFrame; |
mChannelsPerFrame = inChannelsPerFrame; |
mBitsPerChannel = inBitsPerChannel; |
mFormatFlags = inFormatFlags; |
mReserved = 0; |
} |
char *CAStreamBasicDescription::AsString(char *buf, size_t _bufsize) const |
{ |
int bufsize = (int)_bufsize; // must be signed to protect against overflow |
char *theBuffer = buf; |
int nc; |
char formatID[24]; |
CAStringForOSType (mFormatID, formatID); |
nc = snprintf(buf, bufsize, "%2d ch, %6.0f Hz, %s (0x%08X) ", (int)NumberChannels(), mSampleRate, formatID, (int)mFormatFlags); |
buf += nc; if ((bufsize -= nc) <= 0) goto exit; |
if (mFormatID == kAudioFormatLinearPCM) { |
bool isInt = !(mFormatFlags & kLinearPCMFormatFlagIsFloat); |
int wordSize = SampleWordSize(); |
const char *endian = (wordSize > 1) ? |
((mFormatFlags & kLinearPCMFormatFlagIsBigEndian) ? " big-endian" : " little-endian" ) : ""; |
const char *sign = isInt ? |
((mFormatFlags & kLinearPCMFormatFlagIsSignedInteger) ? " signed" : " unsigned") : ""; |
const char *floatInt = isInt ? "integer" : "float"; |
char packed[32]; |
if (wordSize > 0 && PackednessIsSignificant()) { |
if (mFormatFlags & kLinearPCMFormatFlagIsPacked) |
snprintf(packed, sizeof(packed), "packed in %d bytes", wordSize); |
else |
snprintf(packed, sizeof(packed), "unpacked in %d bytes", wordSize); |
} else |
packed[0] = '\0'; |
const char *align = (wordSize > 0 && AlignmentIsSignificant()) ? |
((mFormatFlags & kLinearPCMFormatFlagIsAlignedHigh) ? " high-aligned" : " low-aligned") : ""; |
const char *deinter = (mFormatFlags & kAudioFormatFlagIsNonInterleaved) ? ", deinterleaved" : ""; |
const char *commaSpace = (packed[0]!='\0') || (align[0]!='\0') ? ", " : ""; |
char bitdepth[20]; |
int fracbits = (mFormatFlags & kLinearPCMFormatFlagsSampleFractionMask) >> kLinearPCMFormatFlagsSampleFractionShift; |
if (fracbits > 0) |
snprintf(bitdepth, sizeof(bitdepth), "%d.%d", (int)mBitsPerChannel - fracbits, fracbits); |
else |
snprintf(bitdepth, sizeof(bitdepth), "%d", (int)mBitsPerChannel); |
/* nc =*/ snprintf(buf, bufsize, "%s-bit%s%s %s%s%s%s%s", |
bitdepth, endian, sign, floatInt, |
commaSpace, packed, align, deinter); |
// buf += nc; if ((bufsize -= nc) <= 0) goto exit; |
} else if (mFormatID == 'alac') { // kAudioFormatAppleLossless |
int sourceBits = 0; |
switch (mFormatFlags) |
{ |
case 1: // kAppleLosslessFormatFlag_16BitSourceData |
sourceBits = 16; |
break; |
case 2: // kAppleLosslessFormatFlag_20BitSourceData |
sourceBits = 20; |
break; |
case 3: // kAppleLosslessFormatFlag_24BitSourceData |
sourceBits = 24; |
break; |
case 4: // kAppleLosslessFormatFlag_32BitSourceData |
sourceBits = 32; |
break; |
} |
if (sourceBits) |
nc = snprintf(buf, bufsize, "from %d-bit source, ", sourceBits); |
else |
nc = snprintf(buf, bufsize, "from UNKNOWN source bit depth, "); |
buf += nc; if ((bufsize -= nc) <= 0) goto exit; |
/* nc =*/ snprintf(buf, bufsize, "%d frames/packet", (int)mFramesPerPacket); |
// buf += nc; if ((bufsize -= nc) <= 0) goto exit; |
} |
else |
/* nc =*/ snprintf(buf, bufsize, "%d bits/channel, %d bytes/packet, %d frames/packet, %d bytes/frame", |
(int)mBitsPerChannel, (int)mBytesPerPacket, (int)mFramesPerPacket, (int)mBytesPerFrame); |
exit: |
return theBuffer; |
} |
void CAStreamBasicDescription::NormalizeLinearPCMFormat(AudioStreamBasicDescription& ioDescription) |
{ |
// the only thing that changes is to make mixable linear PCM into the canonical linear PCM format |
if((ioDescription.mFormatID == kAudioFormatLinearPCM) && ((ioDescription.mFormatFlags & kIsNonMixableFlag) == 0)) |
{ |
// the canonical linear PCM format |
ioDescription.mFormatFlags = kAudioFormatFlagsCanonical; |
ioDescription.mBytesPerPacket = SizeOf32(AudioSampleType) * ioDescription.mChannelsPerFrame; |
ioDescription.mFramesPerPacket = 1; |
ioDescription.mBytesPerFrame = SizeOf32(AudioSampleType) * ioDescription.mChannelsPerFrame; |
ioDescription.mBitsPerChannel = 8 * SizeOf32(AudioSampleType); |
} |
} |
void CAStreamBasicDescription::NormalizeLinearPCMFormat(bool inNativeEndian, AudioStreamBasicDescription& ioDescription) |
{ |
// the only thing that changes is to make mixable linear PCM into the canonical linear PCM format |
if((ioDescription.mFormatID == kAudioFormatLinearPCM) && ((ioDescription.mFormatFlags & kIsNonMixableFlag) == 0)) |
{ |
// the canonical linear PCM format |
ioDescription.mFormatFlags = kAudioFormatFlagIsFloat | kAudioFormatFlagIsPacked; |
if(inNativeEndian) |
{ |
#if TARGET_RT_BIG_ENDIAN |
ioDescription.mFormatFlags |= kAudioFormatFlagIsBigEndian; |
#endif |
} |
else |
{ |
#if TARGET_RT_LITTLE_ENDIAN |
ioDescription.mFormatFlags |= kAudioFormatFlagIsBigEndian; |
#endif |
} |
ioDescription.mBytesPerPacket = SizeOf32(AudioSampleType) * ioDescription.mChannelsPerFrame; |
ioDescription.mFramesPerPacket = 1; |
ioDescription.mBytesPerFrame = SizeOf32(AudioSampleType) * ioDescription.mChannelsPerFrame; |
ioDescription.mBitsPerChannel = 8 * SizeOf32(AudioSampleType); |
} |
} |
void CAStreamBasicDescription::ResetFormat(AudioStreamBasicDescription& ioDescription) |
{ |
ioDescription.mSampleRate = 0; |
ioDescription.mFormatID = 0; |
ioDescription.mBytesPerPacket = 0; |
ioDescription.mFramesPerPacket = 0; |
ioDescription.mBytesPerFrame = 0; |
ioDescription.mChannelsPerFrame = 0; |
ioDescription.mBitsPerChannel = 0; |
ioDescription.mFormatFlags = 0; |
} |
void CAStreamBasicDescription::FillOutFormat(AudioStreamBasicDescription& ioDescription, const AudioStreamBasicDescription& inTemplateDescription) |
{ |
if(fiszero(ioDescription.mSampleRate)) |
{ |
ioDescription.mSampleRate = inTemplateDescription.mSampleRate; |
} |
if(ioDescription.mFormatID == 0) |
{ |
ioDescription.mFormatID = inTemplateDescription.mFormatID; |
} |
if(ioDescription.mFormatFlags == 0) |
{ |
ioDescription.mFormatFlags = inTemplateDescription.mFormatFlags; |
} |
if(ioDescription.mBytesPerPacket == 0) |
{ |
ioDescription.mBytesPerPacket = inTemplateDescription.mBytesPerPacket; |
} |
if(ioDescription.mFramesPerPacket == 0) |
{ |
ioDescription.mFramesPerPacket = inTemplateDescription.mFramesPerPacket; |
} |
if(ioDescription.mBytesPerFrame == 0) |
{ |
ioDescription.mBytesPerFrame = inTemplateDescription.mBytesPerFrame; |
} |
if(ioDescription.mChannelsPerFrame == 0) |
{ |
ioDescription.mChannelsPerFrame = inTemplateDescription.mChannelsPerFrame; |
} |
if(ioDescription.mBitsPerChannel == 0) |
{ |
ioDescription.mBitsPerChannel = inTemplateDescription.mBitsPerChannel; |
} |
} |
void CAStreamBasicDescription::GetSimpleName(const AudioStreamBasicDescription& inDescription, char* outName, UInt32 inMaxNameLength, bool inAbbreviate, bool inIncludeSampleRate) |
{ |
if(inIncludeSampleRate) |
{ |
int theCharactersWritten = snprintf(outName, inMaxNameLength, "%.0f ", inDescription.mSampleRate); |
outName += theCharactersWritten; |
inMaxNameLength -= theCharactersWritten; |
} |
switch(inDescription.mFormatID) |
{ |
case kAudioFormatLinearPCM: |
{ |
const char* theEndianString = NULL; |
if((inDescription.mFormatFlags & kAudioFormatFlagIsBigEndian) != 0) |
{ |
#if TARGET_RT_LITTLE_ENDIAN |
theEndianString = "Big Endian"; |
#endif |
} |
else |
{ |
#if TARGET_RT_BIG_ENDIAN |
theEndianString = "Little Endian"; |
#endif |
} |
const char* theKindString = NULL; |
if((inDescription.mFormatFlags & kAudioFormatFlagIsFloat) != 0) |
{ |
theKindString = (inAbbreviate ? "Float" : "Floating Point"); |
} |
else if((inDescription.mFormatFlags & kAudioFormatFlagIsSignedInteger) != 0) |
{ |
theKindString = (inAbbreviate ? "SInt" : "Signed Integer"); |
} |
else |
{ |
theKindString = (inAbbreviate ? "UInt" : "Unsigned Integer"); |
} |
const char* thePackingString = NULL; |
if((inDescription.mFormatFlags & kAudioFormatFlagIsPacked) == 0) |
{ |
if((inDescription.mFormatFlags & kAudioFormatFlagIsAlignedHigh) != 0) |
{ |
thePackingString = "High"; |
} |
else |
{ |
thePackingString = "Low"; |
} |
} |
const char* theMixabilityString = NULL; |
if((inDescription.mFormatFlags & kIsNonMixableFlag) == 0) |
{ |
theMixabilityString = "Mixable"; |
} |
else |
{ |
theMixabilityString = "Unmixable"; |
} |
if(inAbbreviate) |
{ |
if(theEndianString != NULL) |
{ |
if(thePackingString != NULL) |
{ |
snprintf(outName, inMaxNameLength, "%s %d Ch %s %s %s%d/%s%d", theMixabilityString, (int)inDescription.mChannelsPerFrame, theEndianString, thePackingString, theKindString, (int)inDescription.mBitsPerChannel, theKindString, (int)(inDescription.mBytesPerFrame / inDescription.mChannelsPerFrame) * 8); |
} |
else |
{ |
snprintf(outName, inMaxNameLength, "%s %d Ch %s %s%d", theMixabilityString, (int)inDescription.mChannelsPerFrame, theEndianString, theKindString, (int)inDescription.mBitsPerChannel); |
} |
} |
else |
{ |
if(thePackingString != NULL) |
{ |
snprintf(outName, inMaxNameLength, "%s %d Ch %s %s%d/%s%d", theMixabilityString, (int)inDescription.mChannelsPerFrame, thePackingString, theKindString, (int)inDescription.mBitsPerChannel, theKindString, (int)((inDescription.mBytesPerFrame / inDescription.mChannelsPerFrame) * 8)); |
} |
else |
{ |
snprintf(outName, inMaxNameLength, "%s %d Ch %s%d", theMixabilityString, (int)inDescription.mChannelsPerFrame, theKindString, (int)inDescription.mBitsPerChannel); |
} |
} |
} |
else |
{ |
if(theEndianString != NULL) |
{ |
if(thePackingString != NULL) |
{ |
snprintf(outName, inMaxNameLength, "%s %d Channel %d Bit %s %s Aligned %s in %d Bits", theMixabilityString, (int)inDescription.mChannelsPerFrame, (int)inDescription.mBitsPerChannel, theEndianString, theKindString, thePackingString, (int)(inDescription.mBytesPerFrame / inDescription.mChannelsPerFrame) * 8); |
} |
else |
{ |
snprintf(outName, inMaxNameLength, "%s %d Channel %d Bit %s %s", theMixabilityString, (int)inDescription.mChannelsPerFrame, (int)inDescription.mBitsPerChannel, theEndianString, theKindString); |
} |
} |
else |
{ |
if(thePackingString != NULL) |
{ |
snprintf(outName, inMaxNameLength, "%s %d Channel %d Bit %s Aligned %s in %d Bits", theMixabilityString, (int)inDescription.mChannelsPerFrame, (int)inDescription.mBitsPerChannel, theKindString, thePackingString, (int)(inDescription.mBytesPerFrame / inDescription.mChannelsPerFrame) * 8); |
} |
else |
{ |
snprintf(outName, inMaxNameLength, "%s %d Channel %d Bit %s", theMixabilityString, (int)inDescription.mChannelsPerFrame, (int)inDescription.mBitsPerChannel, theKindString); |
} |
} |
} |
} |
break; |
case kAudioFormatAC3: |
strlcpy(outName, "AC-3", sizeof(outName)); |
break; |
case kAudioFormat60958AC3: |
strlcpy(outName, "AC-3 for SPDIF", sizeof(outName)); |
break; |
default: |
CACopy4CCToCString(outName, inDescription.mFormatID); |
break; |
}; |
} |
#if CoreAudio_Debug |
#include "CALogMacros.h" |
void CAStreamBasicDescription::PrintToLog(const AudioStreamBasicDescription& inDesc) |
{ |
PrintFloat (" Sample Rate: ", inDesc.mSampleRate); |
Print4CharCode (" Format ID: ", inDesc.mFormatID); |
PrintHex (" Format Flags: ", inDesc.mFormatFlags); |
PrintInt (" Bytes per Packet: ", inDesc.mBytesPerPacket); |
PrintInt (" Frames per Packet: ", inDesc.mFramesPerPacket); |
PrintInt (" Bytes per Frame: ", inDesc.mBytesPerFrame); |
PrintInt (" Channels per Frame: ", inDesc.mChannelsPerFrame); |
PrintInt (" Bits per Channel: ", inDesc.mBitsPerChannel); |
} |
#endif |
bool operator<(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y) |
{ |
bool theAnswer = false; |
bool isDone = false; |
// note that if either side is 0, that field is skipped |
// format ID is the first order sort |
if((!isDone) && ((x.mFormatID != 0) && (y.mFormatID != 0))) |
{ |
if(x.mFormatID != y.mFormatID) |
{ |
// formats are sorted numerically except that linear |
// PCM is always first |
if(x.mFormatID == kAudioFormatLinearPCM) |
{ |
theAnswer = true; |
} |
else if(y.mFormatID == kAudioFormatLinearPCM) |
{ |
theAnswer = false; |
} |
else |
{ |
theAnswer = x.mFormatID < y.mFormatID; |
} |
isDone = true; |
} |
} |
// mixable is always better than non-mixable for linear PCM and should be the second order sort item |
if((!isDone) && ((x.mFormatID == kAudioFormatLinearPCM) && (y.mFormatID == kAudioFormatLinearPCM))) |
{ |
if(((x.mFormatFlags & kIsNonMixableFlag) == 0) && ((y.mFormatFlags & kIsNonMixableFlag) != 0)) |
{ |
theAnswer = true; |
isDone = true; |
} |
else if(((x.mFormatFlags & kIsNonMixableFlag) != 0) && ((y.mFormatFlags & kIsNonMixableFlag) == 0)) |
{ |
theAnswer = false; |
isDone = true; |
} |
} |
// floating point vs integer for linear PCM only |
if((!isDone) && ((x.mFormatID == kAudioFormatLinearPCM) && (y.mFormatID == kAudioFormatLinearPCM))) |
{ |
if((x.mFormatFlags & kAudioFormatFlagIsFloat) != (y.mFormatFlags & kAudioFormatFlagIsFloat)) |
{ |
// floating point is better than integer |
theAnswer = y.mFormatFlags & kAudioFormatFlagIsFloat; |
isDone = true; |
} |
} |
// bit depth |
if((!isDone) && ((x.mBitsPerChannel != 0) && (y.mBitsPerChannel != 0))) |
{ |
if(x.mBitsPerChannel != y.mBitsPerChannel) |
{ |
// deeper bit depths are higher quality |
theAnswer = x.mBitsPerChannel < y.mBitsPerChannel; |
isDone = true; |
} |
} |
// sample rate |
if((!isDone) && fnonzero(x.mSampleRate) && fnonzero(y.mSampleRate)) |
{ |
if(fnotequal(x.mSampleRate, y.mSampleRate)) |
{ |
// higher sample rates are higher quality |
theAnswer = x.mSampleRate < y.mSampleRate; |
isDone = true; |
} |
} |
// number of channels |
if((!isDone) && ((x.mChannelsPerFrame != 0) && (y.mChannelsPerFrame != 0))) |
{ |
if(x.mChannelsPerFrame != y.mChannelsPerFrame) |
{ |
// more channels is higher quality |
theAnswer = x.mChannelsPerFrame < y.mChannelsPerFrame; |
//isDone = true; |
} |
} |
return theAnswer; |
} |
static bool MatchFormatFlags(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y) |
{ |
UInt32 xFlags = x.mFormatFlags; |
UInt32 yFlags = y.mFormatFlags; |
// match wildcards |
if (x.mFormatID == 0 || y.mFormatID == 0 || xFlags == 0 || yFlags == 0) |
return true; |
if (x.mFormatID == kAudioFormatLinearPCM) |
{ |
// knock off the all clear flag |
xFlags = xFlags & ~kAudioFormatFlagsAreAllClear; |
yFlags = yFlags & ~kAudioFormatFlagsAreAllClear; |
// if both kAudioFormatFlagIsPacked bits are set, then we don't care about the kAudioFormatFlagIsAlignedHigh bit. |
if (xFlags & yFlags & kAudioFormatFlagIsPacked) { |
xFlags = xFlags & ~kAudioFormatFlagIsAlignedHigh; |
yFlags = yFlags & ~kAudioFormatFlagIsAlignedHigh; |
} |
// if both kAudioFormatFlagIsFloat bits are set, then we don't care about the kAudioFormatFlagIsSignedInteger bit. |
if (xFlags & yFlags & kAudioFormatFlagIsFloat) { |
xFlags = xFlags & ~kAudioFormatFlagIsSignedInteger; |
yFlags = yFlags & ~kAudioFormatFlagIsSignedInteger; |
} |
// if the bit depth is 8 bits or less and the format is packed, we don't care about endianness |
if((x.mBitsPerChannel <= 8) && ((xFlags & kAudioFormatFlagIsPacked) == kAudioFormatFlagIsPacked)) |
{ |
xFlags = xFlags & ~kAudioFormatFlagIsBigEndian; |
} |
if((y.mBitsPerChannel <= 8) && ((yFlags & kAudioFormatFlagIsPacked) == kAudioFormatFlagIsPacked)) |
{ |
yFlags = yFlags & ~kAudioFormatFlagIsBigEndian; |
} |
// if the number of channels is 1, we don't care about non-interleavedness |
if (x.mChannelsPerFrame == 1 && y.mChannelsPerFrame == 1) { |
xFlags &= ~kLinearPCMFormatFlagIsNonInterleaved; |
yFlags &= ~kLinearPCMFormatFlagIsNonInterleaved; |
} |
} |
return xFlags == yFlags; |
} |
bool operator==(const AudioStreamBasicDescription& x, const AudioStreamBasicDescription& y) |
{ |
// the semantics for equality are: |
// 1) Values must match exactly -- except for PCM format flags, see above. |
// 2) wildcard's are ignored in the comparison |
#define MATCH(name) ((x.name) == 0 || (y.name) == 0 || (x.name) == (y.name)) |
return |
// check the sample rate |
(fiszero(x.mSampleRate) || fiszero(y.mSampleRate) || fequal(x.mSampleRate, y.mSampleRate)) |
// check the format ids |
&& MATCH(mFormatID) |
// check the format flags |
&& MatchFormatFlags(x, y) |
// check the bytes per packet |
&& MATCH(mBytesPerPacket) |
// check the frames per packet |
&& MATCH(mFramesPerPacket) |
// check the bytes per frame |
&& MATCH(mBytesPerFrame) |
// check the channels per frame |
&& MATCH(mChannelsPerFrame) |
// check the channels per frame |
&& MATCH(mBitsPerChannel) ; |
} |
bool CAStreamBasicDescription::IsEqual(const AudioStreamBasicDescription &other, bool interpretingWildcards) const |
{ |
if (interpretingWildcards) |
return *this == other; |
return memcmp(this, &other, offsetof(AudioStreamBasicDescription, mReserved)) == 0; |
} |
bool SanityCheck(const AudioStreamBasicDescription& x) |
{ |
// This function returns false if there are sufficiently insane values in any field. |
// It is very conservative so even some very unlikely values will pass. |
// This is just meant to catch the case where the data from a file is corrupted. |
return |
(x.mSampleRate >= 0.) |
&& (x.mSampleRate < 3e6) // SACD sample rate is 2.8224 MHz |
&& (x.mBytesPerPacket < 1000000) |
&& (x.mFramesPerPacket < 1000000) |
&& (x.mBytesPerFrame < 1000000) |
&& (x.mChannelsPerFrame <= 1024) |
&& (x.mBitsPerChannel <= 1024) |
&& (x.mFormatID != 0) |
&& !(x.mFormatID == kAudioFormatLinearPCM && (x.mFramesPerPacket != 1 || x.mBytesPerPacket != x.mBytesPerFrame)); |
} |
bool CAStreamBasicDescription::FromText(const char *inTextDesc, AudioStreamBasicDescription &fmt) |
{ |
const char *p = inTextDesc; |
memset(&fmt, 0, sizeof(fmt)); |
bool isPCM = true; // until proven otherwise |
UInt32 pcmFlags = kAudioFormatFlagIsPacked | kAudioFormatFlagIsSignedInteger; |
if (p[0] == '-') // previously we required a leading dash on PCM formats |
++p; |
if (p[0] == 'B' && p[1] == 'E') { |
pcmFlags |= kLinearPCMFormatFlagIsBigEndian; |
p += 2; |
} else if (p[0] == 'L' && p[1] == 'E') { |
p += 2; |
} else { |
// default is native-endian |
#if TARGET_RT_BIG_ENDIAN |
pcmFlags |= kLinearPCMFormatFlagIsBigEndian; |
#endif |
} |
if (p[0] == 'F') { |
pcmFlags = (pcmFlags & ~kAudioFormatFlagIsSignedInteger) | kAudioFormatFlagIsFloat; |
++p; |
} else { |
if (p[0] == 'U') { |
pcmFlags &= ~kAudioFormatFlagIsSignedInteger; |
++p; |
} |
if (p[0] == 'I') |
++p; |
else { |
// it's not PCM; presumably some other format (NOT VALIDATED; use AudioFormat for that) |
isPCM = false; |
p = inTextDesc; // go back to the beginning |
char buf[4] = { ' ',' ',' ',' ' }; |
for (int i = 0; i < 4; ++i) { |
if (*p != '\\') { |
if ((buf[i] = *p++) == '\0') { |
// special-case for 'aac' |
if (i != 3) return false; |
--p; // keep pointing at the terminating null |
buf[i] = ' '; |
break; |
} |
} else { |
// "\xNN" is a hex byte |
if (*++p != 'x') return false; |
int x; |
if (sscanf(++p, "%02X", &x) != 1) return false; |
buf[i] = x; |
p += 2; |
} |
} |
if (strchr("-@/#", buf[3])) { |
// further special-casing for 'aac' |
buf[3] = ' '; |
--p; |
} |
fmt.mFormatID = CFSwapInt32BigToHost(*(UInt32 *)buf); |
} |
} |
if (isPCM) { |
fmt.mFormatID = kAudioFormatLinearPCM; |
fmt.mFormatFlags = pcmFlags; |
fmt.mFramesPerPacket = 1; |
fmt.mChannelsPerFrame = 1; |
int bitdepth = 0, fracbits = 0; |
while (isdigit(*p)) |
bitdepth = 10 * bitdepth + *p++ - '0'; |
if (*p == '.') { |
++p; |
if (!isdigit(*p)) { |
fprintf(stderr, "Expected fractional bits following '.'\n"); |
goto Bail; |
} |
while (isdigit(*p)) |
fracbits = 10 * fracbits + *p++ - '0'; |
bitdepth += fracbits; |
fmt.mFormatFlags |= (fracbits << kLinearPCMFormatFlagsSampleFractionShift); |
} |
fmt.mBitsPerChannel = bitdepth; |
fmt.mBytesPerPacket = fmt.mBytesPerFrame = (bitdepth + 7) / 8; |
if (bitdepth & 7) { |
// assume unpacked. (packed odd bit depths are describable but not supported in AudioConverter.) |
fmt.mFormatFlags &= ~kLinearPCMFormatFlagIsPacked; |
// alignment matters; default to high-aligned. use ':L_' for low. |
fmt.mFormatFlags |= kLinearPCMFormatFlagIsAlignedHigh; |
} |
} |
if (*p == '@') { |
++p; |
while (isdigit(*p)) |
fmt.mSampleRate = 10 * fmt.mSampleRate + (*p++ - '0'); |
} |
if (*p == '/') { |
UInt32 flags = 0; |
while (true) { |
char c = *++p; |
if (c >= '0' && c <= '9') |
flags = (flags << 4) | (c - '0'); |
else if (c >= 'A' && c <= 'F') |
flags = (flags << 4) | (c - 'A' + 10); |
else if (c >= 'a' && c <= 'f') |
flags = (flags << 4) | (c - 'a' + 10); |
else break; |
} |
fmt.mFormatFlags = flags; |
} |
if (*p == '#') { |
++p; |
while (isdigit(*p)) |
fmt.mFramesPerPacket = 10 * fmt.mFramesPerPacket + (*p++ - '0'); |
} |
if (*p == ':') { |
++p; |
fmt.mFormatFlags &= ~kLinearPCMFormatFlagIsPacked; |
if (*p == 'L') |
fmt.mFormatFlags &= ~kLinearPCMFormatFlagIsAlignedHigh; |
else if (*p == 'H') |
fmt.mFormatFlags |= kLinearPCMFormatFlagIsAlignedHigh; |
else |
goto Bail; |
++p; |
int bytesPerFrame = 0; |
while (isdigit(*p)) |
bytesPerFrame = 10 * bytesPerFrame + (*p++ - '0'); |
fmt.mBytesPerFrame = fmt.mBytesPerPacket = bytesPerFrame; |
} |
if (*p == ',') { |
++p; |
int ch = 0; |
while (isdigit(*p)) |
ch = 10 * ch + (*p++ - '0'); |
fmt.mChannelsPerFrame = ch; |
if (*p == 'D') { |
++p; |
if (fmt.mFormatID != kAudioFormatLinearPCM) { |
fprintf(stderr, "non-interleaved flag invalid for non-PCM formats\n"); |
goto Bail; |
} |
fmt.mFormatFlags |= kAudioFormatFlagIsNonInterleaved; |
} else { |
if (*p == 'I') ++p; // default |
if (fmt.mFormatID == kAudioFormatLinearPCM) |
fmt.mBytesPerPacket = fmt.mBytesPerFrame *= ch; |
} |
} |
if (*p != '\0') { |
fprintf(stderr, "extra characters at end of format string: %s\n", p); |
goto Bail; |
} |
return true; |
Bail: |
fprintf(stderr, "Invalid format string: %s\n", inTextDesc); |
fprintf(stderr, "Syntax of format strings is: \n"); |
return false; |
} |
const char *CAStreamBasicDescription::sTextParsingUsageString = |
"format[@sample_rate_hz][/format_flags][#frames_per_packet][:LHbytesPerFrame][,channelsDI].\n" |
"Format for PCM is [-][BE|LE]{F|I|UI}{bitdepth}; else a 4-char format code (e.g. aac, alac).\n"; |
Copyright © 2012 Apple Inc. All Rights Reserved. Terms of Use | Privacy Policy | Updated: 2012-10-08