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Make PCM WAV reading (almost) machine endian neutral. The actual sample data read are still assumed to be in machine endian, which will produce garbage output on big endian archs.

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Originally committed to SVN as r2222.
This commit is contained in:
Niels Martin Hansen 2008-07-03 02:22:18 +00:00
parent 8384e83e71
commit a7b64fe694
1 changed files with 14 additions and 11 deletions
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25
aegisub/audio_provider_pcm.cpp
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@ -38,6 +38,7 @@
#include <wx/file.h> #include <wx/file.h>
#include "audio_provider_pcm.h" #include "audio_provider_pcm.h"
#include "utils.h" #include "utils.h"
#include "endian.h"
#include <stdint.h> #include <stdint.h>
#ifndef _WINDOWS #ifndef _WINDOWS
@ -240,7 +241,7 @@ class RiffWavPCMAudioProvider : public PCMAudioProvider {
private: private:
struct ChunkHeader { struct ChunkHeader {
char type[4]; char type[4];
uint32_t size; // XXX: Assume we're compiling on little endian uint32_t size;
}; };
struct RIFFChunk { struct RIFFChunk {
ChunkHeader ch; ChunkHeader ch;
@ -248,7 +249,7 @@ private:
}; };
struct fmtChunk { struct fmtChunk {
// Skip the chunk header here, it's processed separately // Skip the chunk header here, it's processed separately
uint16_t compression; // compression format used -- 0x01 = PCM uint16_t compression; // compression format used -- 0x0001 = PCM
uint16_t channels; uint16_t channels;
uint32_t samplerate; uint32_t samplerate;
uint32_t avg_bytes_sec; // can't always be trusted uint32_t avg_bytes_sec; // can't always be trusted
@ -276,7 +277,7 @@ public:
// Count how much more data we can have in the entire file // Count how much more data we can have in the entire file
// The first 4 bytes are already eaten by the header.format field // The first 4 bytes are already eaten by the header.format field
uint32_t data_left = header.ch.size - 4; uint32_t data_left = Endian::LittleToMachine(header.ch.size) - 4;
// How far into the file we have processed. // How far into the file we have processed.
// Must be incremented by the riff chunk size fields. // Must be incremented by the riff chunk size fields.
uint32_t filepos = sizeof(header); uint32_t filepos = sizeof(header);
@ -300,19 +301,21 @@ public:
fmtChunk &fmt = *(fmtChunk*)EnsureRangeAccessible(filepos, sizeof(fmtChunk)); fmtChunk &fmt = *(fmtChunk*)EnsureRangeAccessible(filepos, sizeof(fmtChunk));
if (fmt.compression != 1) throw _T("RIFF PCM WAV audio provider: Can't use file, not PCM encoding"); if (Endian::LittleToMachine(fmt.compression) != 1) throw _T("RIFF PCM WAV audio provider: Can't use file, not PCM encoding");
// Set stuff inherited from the AudioProvider class // Set stuff inherited from the AudioProvider class
sample_rate = fmt.samplerate; sample_rate = Endian::LittleToMachine(fmt.samplerate);
channels = fmt.channels; channels = Endian::LittleToMachine(fmt.channels);
bytes_per_sample = (fmt.significant_bits_sample + 7) / 8; // round up to nearest whole byte bytes_per_sample = (Endian::LittleToMachine(fmt.significant_bits_sample) + 7) / 8; // round up to nearest whole byte
} }
else if (strncmp(ch.type, "data", 4) == 0) { else if (strncmp(ch.type, "data", 4) == 0) {
// This won't pick up 'data' chunks inside 'wavl' chunks // This won't pick up 'data' chunks inside 'wavl' chunks
// since the 'wavl' chunks wrap those. // since the 'wavl' chunks wrap those.
int64_t samples = ch.size / bytes_per_sample; if (!got_fmt_header) throw _T("RIFF PCM WAV audio provider: Found 'data' chunk before 'fmt ' chunk, file is invalid.");
int64_t samples = Endian::LittleToMachine(ch.size) / bytes_per_sample;
int64_t frames = samples / channels; int64_t frames = samples / channels;
IndexPoint ip; IndexPoint ip;
@ -328,8 +331,8 @@ public:
// Update counters // Update counters
// Make sure they're word aligned // Make sure they're word aligned
data_left -= (ch.size + 1) & ~1; data_left -= (Endian::LittleToMachine(ch.size) + 1) & ~1;
filepos += (ch.size + 1) & ~1; filepos += (Endian::LittleToMachine(ch.size) + 1) & ~1;
} }
} }
}; };
@ -388,6 +391,7 @@ public:
// Now downmix // Now downmix
// Just average the samples over the channels (really bad if they're out of phase!) // Just average the samples over the channels (really bad if they're out of phase!)
// XXX: Assuming here that sample data are in machine endian, an upstream provider should ensure that
if (bytes_per_sample == 1) { if (bytes_per_sample == 1) {
uint8_t *src = (uint8_t *)tmp; uint8_t *src = (uint8_t *)tmp;
uint8_t *dst = (uint8_t *)buf; uint8_t *dst = (uint8_t *)buf;
@ -424,7 +428,6 @@ AudioProvider *CreatePCMAudioProvider(const wxString &filename)
AudioProvider *provider = 0; AudioProvider *provider = 0;
// Try Microsoft/IBM RIFF WAV first // Try Microsoft/IBM RIFF WAV first
// XXX: This is going to blow up if built on big endian archs
try { try {
provider = new RiffWavPCMAudioProvider(filename); provider = new RiffWavPCMAudioProvider(filename);
} }