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Skip XING/VBRI frame when decoding

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Don't send the XING/VBRI frame to the decoder, as it will result in
extra data being output. Also clean up the XING seeker code a bit.

Change-Id: I714a94180edae9bedc1bc0c96bf382fe6f928ac6
This commit is contained in:
Marco Nelissen
2012-03-16 07:56:42 -07:00
parent b411579667
commit 4fc769e9df
3 changed files with 59 additions and 107 deletions
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7
media/libstagefright/MP3Extractor.cpp
View File

@@ -317,6 +317,13 @@ MP3Extractor::MP3Extractor(
mSeeker = VBRISeeker::CreateFromSource(mDataSource, post_id3_pos);
}
if (mSeeker != NULL) {
// While it is safe to send the XING/VBRI frame to the decoder, this will
// result in an extra 1152 samples being output. The real first frame to
// decode is after the XING/VBRI frame, so skip there.
mFirstFramePos += frame_size;
}
int64_t durationUs;
if (mSeeker == NULL || !mSeeker->getDuration(&durationUs)) {

2
media/libstagefright/VBRISeeker.cpp
View File

@@ -92,7 +92,7 @@ sp<VBRISeeker> VBRISeeker::CreateFromSource(
}
sp<VBRISeeker> seeker = new VBRISeeker;
seeker->mBasePos = post_id3_pos;
seeker->mBasePos = post_id3_pos + frameSize;
seeker->mDurationUs = durationUs;
off64_t offset = post_id3_pos;

157
media/libstagefright/XINGSeeker.cpp
View File

@@ -15,35 +15,13 @@
*/
#include "include/XINGSeeker.h"
#include "include/avc_utils.h"
#include <media/stagefright/DataSource.h>
#include <media/stagefright/Utils.h>
namespace android {
static bool parse_xing_header(
const sp<DataSource> &source, off64_t first_frame_pos,
int32_t *frame_number = NULL, int32_t *byte_number = NULL,
unsigned char *table_of_contents = NULL, bool *toc_is_valid = NULL,
int32_t *quality_indicator = NULL, int64_t *duration = NULL);
// static
sp<XINGSeeker> XINGSeeker::CreateFromSource(
const sp<DataSource> &source, off64_t first_frame_pos) {
sp<XINGSeeker> seeker = new XINGSeeker;
seeker->mFirstFramePos = first_frame_pos;
if (!parse_xing_header(
source, first_frame_pos,
NULL, &seeker->mSizeBytes, seeker->mTOC, &seeker->mTOCValid,
NULL, &seeker->mDurationUs)) {
return NULL;
}
return seeker;
}
XINGSeeker::XINGSeeker()
: mDurationUs(-1),
mSizeBytes(0) {
@@ -91,60 +69,50 @@ bool XINGSeeker::getOffsetForTime(int64_t *timeUs, off64_t *pos) {
return true;
}
static bool parse_xing_header(
const sp<DataSource> &source, off64_t first_frame_pos,
int32_t *frame_number, int32_t *byte_number,
unsigned char *table_of_contents, bool *toc_valid,
int32_t *quality_indicator,
int64_t *duration) {
if (frame_number) {
*frame_number = 0;
}
if (byte_number) {
*byte_number = 0;
}
if (toc_valid) {
*toc_valid = false;
}
if (quality_indicator) {
*quality_indicator = 0;
}
if (duration) {
*duration = 0;
}
// static
sp<XINGSeeker> XINGSeeker::CreateFromSource(
const sp<DataSource> &source, off64_t first_frame_pos) {
sp<XINGSeeker> seeker = new XINGSeeker;
seeker->mFirstFramePos = first_frame_pos;
ALOGI("xingseeker first frame pos: %lld", first_frame_pos);
seeker->mSizeBytes = 0;
seeker->mTOCValid = false;
seeker->mDurationUs = 0;
uint8_t buffer[4];
int offset = first_frame_pos;
if (source->readAt(offset, &buffer, 4) < 4) { // get header
return false;
return NULL;
}
offset += 4;
uint8_t id, layer, sr_index, mode;
layer = (buffer[1] >> 1) & 3;
id = (buffer[1] >> 3) & 3;
sr_index = (buffer[2] >> 2) & 3;
mode = (buffer[3] >> 6) & 3;
if (layer == 0) {
return false;
}
if (id == 1) {
return false;
}
if (sr_index == 3) {
return false;
int header = U32_AT(buffer);;
size_t xingframesize = 0;
int sampling_rate = 0;
int num_channels;
int samples_per_frame = 0;
if (!GetMPEGAudioFrameSize(header, &xingframesize, &sampling_rate, &num_channels,
NULL, &samples_per_frame)) {
return NULL;
}
seeker->mFirstFramePos += xingframesize;
uint8_t version = (buffer[1] >> 3) & 3;
// determine offset of XING header
if(id&1) { // mpeg1
if (mode != 3) offset += 32;
if(version & 1) { // mpeg1
if (num_channels != 1) offset += 32;
else offset += 17;
} else { // mpeg2
if (mode != 3) offset += 17;
} else { // mpeg 2 or 2.5
if (num_channels != 1) offset += 17;
else offset += 9;
}
if (source->readAt(offset, &buffer, 4) < 4) { // XING header ID
return false;
return NULL;
}
offset += 4;
// Check XING ID
@@ -152,73 +120,50 @@ static bool parse_xing_header(
|| (buffer[2] != 'n') || (buffer[3] != 'g')) {
if ((buffer[0] != 'I') || (buffer[1] != 'n')
|| (buffer[2] != 'f') || (buffer[3] != 'o')) {
return false;
return NULL;
}
}
if (source->readAt(offset, &buffer, 4) < 4) { // flags
return false;
return NULL;
}
offset += 4;
uint32_t flags = U32_AT(buffer);
if (flags & 0x0001) { // Frames field is present
if (source->readAt(offset, buffer, 4) < 4) {
return false;
}
if (frame_number) {
*frame_number = U32_AT(buffer);
}
int32_t frame = U32_AT(buffer);
// Samples per Frame: 1. index = MPEG Version ID, 2. index = Layer
const int samplesPerFrames[2][3] =
{
{ 384, 1152, 576 }, // MPEG 2, 2.5: layer1, layer2, layer3
{ 384, 1152, 1152 }, // MPEG 1: layer1, layer2, layer3
};
// sampling rates in hertz: 1. index = MPEG Version ID, 2. index = sampling rate index
const int samplingRates[4][3] =
{
{ 11025, 12000, 8000, }, // MPEG 2.5
{ 0, 0, 0, }, // reserved
{ 22050, 24000, 16000, }, // MPEG 2
{ 44100, 48000, 32000, } // MPEG 1
};
if (duration) {
*duration = (int64_t)frame * samplesPerFrames[id&1][3-layer] * 1000000LL
/ samplingRates[id][sr_index];
return NULL;
}
int32_t frames = U32_AT(buffer);
seeker->mDurationUs = (int64_t)frames * samples_per_frame * 1000000LL / sampling_rate;
offset += 4;
}
if (flags & 0x0002) { // Bytes field is present
if (byte_number) {
if (source->readAt(offset, buffer, 4) < 4) {
return false;
}
*byte_number = U32_AT(buffer);
if (source->readAt(offset, buffer, 4) < 4) {
return NULL;
}
seeker->mSizeBytes = U32_AT(buffer);
offset += 4;
}
if (flags & 0x0004) { // TOC field is present
if (table_of_contents) {
if (source->readAt(offset + 1, table_of_contents, 99) < 99) {
return false;
}
if (toc_valid) {
*toc_valid = true;
}
if (source->readAt(offset + 1, seeker->mTOC, 99) < 99) {
return NULL;
}
seeker->mTOCValid = true;
offset += 100;
}
#if 0
if (flags & 0x0008) { // Quality indicator field is present
if (quality_indicator) {
if (source->readAt(offset, buffer, 4) < 4) {
return false;
}
*quality_indicator = U32_AT(buffer);
if (source->readAt(offset, buffer, 4) < 4) {
return NULL;
}
// do something with the quality indicator
offset += 4;
}
return true;
#endif
return seeker;
}
} // namespace android