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Diffstat (limited to 'media/libstagefright/XINGSeeker.cpp')
| -rw-r--r-- | media/libstagefright/XINGSeeker.cpp | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/media/libstagefright/XINGSeeker.cpp b/media/libstagefright/XINGSeeker.cpp new file mode 100644 index 0000000..9c91134 --- /dev/null +++ b/media/libstagefright/XINGSeeker.cpp @@ -0,0 +1,196 @@ +/* + * Copyright (C) 2010 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#define LOG_TAG "XINGSEEKER" +#include <utils/Log.h> + +#include "include/XINGSeeker.h" +#include "include/avc_utils.h" + +#include <media/stagefright/DataSource.h> +#include <media/stagefright/Utils.h> + +namespace android { + +XINGSeeker::XINGSeeker() + : mDurationUs(-1), + mSizeBytes(0), + mEncoderDelay(0), + mEncoderPadding(0) { +} + +bool XINGSeeker::getDuration(int64_t *durationUs) { + if (mDurationUs < 0) { + return false; + } + + *durationUs = mDurationUs; + + return true; +} + +bool XINGSeeker::getOffsetForTime(int64_t *timeUs, off64_t *pos) { + if (mSizeBytes == 0 || !mTOCValid || mDurationUs < 0) { + return false; + } + + float percent = (float)(*timeUs) * 100 / mDurationUs; + float fx; + if( percent <= 0.0f ) { + fx = 0.0f; + } else if( percent >= 100.0f ) { + fx = 256.0f; + } else { + int a = (int)percent; + float fa, fb; + if ( a == 0 ) { + fa = 0.0f; + } else { + fa = (float)mTOC[a-1]; + } + if ( a < 99 ) { + fb = (float)mTOC[a]; + } else { + fb = 256.0f; + } + fx = fa + (fb-fa)*(percent-a); + } + + *pos = (int)((1.0f/256.0f)*fx*mSizeBytes) + mFirstFramePos; + + return true; +} + +// static +sp<XINGSeeker> XINGSeeker::CreateFromSource( + const sp<DataSource> &source, off64_t first_frame_pos) { + sp<XINGSeeker> seeker = new XINGSeeker; + + seeker->mFirstFramePos = 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 NULL; + } + offset += 4; + + 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(version & 1) { // mpeg1 + if (num_channels != 1) offset += 32; + else offset += 17; + } else { // mpeg 2 or 2.5 + if (num_channels != 1) offset += 17; + else offset += 9; + } + + int xingbase = offset; + + if (source->readAt(offset, &buffer, 4) < 4) { // XING header ID + return NULL; + } + offset += 4; + // Check XING ID + if ((buffer[0] != 'X') || (buffer[1] != 'i') + || (buffer[2] != 'n') || (buffer[3] != 'g')) { + if ((buffer[0] != 'I') || (buffer[1] != 'n') + || (buffer[2] != 'f') || (buffer[3] != 'o')) { + return NULL; + } + } + + if (source->readAt(offset, &buffer, 4) < 4) { // flags + 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 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 (source->readAt(offset, buffer, 4) < 4) { + return NULL; + } + seeker->mSizeBytes = U32_AT(buffer); + offset += 4; + } + if (flags & 0x0004) { // TOC field is present + 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 (source->readAt(offset, buffer, 4) < 4) { + return NULL; + } + // do something with the quality indicator + offset += 4; + } + + if (source->readAt(xingbase + 0xaf - 0x24, &buffer, 1) < 1) { // encoding flags + return false; + } + + ALOGV("nogap preceding: %s, nogap continued in next: %s", + (buffer[0] & 0x80) ? "true" : "false", + (buffer[0] & 0x40) ? "true" : "false"); +#endif + + if (source->readAt(xingbase + 0xb1 - 0x24, &buffer, 3) == 3) { + seeker->mEncoderDelay = (buffer[0] << 4) + (buffer[1] >> 4); + seeker->mEncoderPadding = ((buffer[1] & 0xf) << 8) + buffer[2]; + } + + return seeker; +} + +int32_t XINGSeeker::getEncoderDelay() { + return mEncoderDelay; +} + +int32_t XINGSeeker::getEncoderPadding() { + return mEncoderPadding; +} + +} // namespace android + |