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Commit 0d34d8b4 authored by Andreas Huber's avatar Andreas Huber
Browse files

Skip any number of leading ID3v2 tags (instead of just the first), also... 

Skip any number of leading ID3v2 tags (instead of just the first), also simplify/fix the find-consecutive-mp3-frames functionality.

Change-Id: I30b93b21de9bd5509b617cca21f46331562c30ac
related-to-bug: 2553445
parent 95a321fc

media/libstagefright/MP3Extractor.cpp

+31 −51
Original line number Diff line number Diff line
@@ -311,15 +311,19 @@ static bool Resync( 
        // Skip an optional ID3 header if syncing at the very beginning

        // of the datasource.



        for (;;) {

            uint8_t id3header[10];

        if (source->readAt(0, id3header, sizeof(id3header))

            if (source->readAt(*inout_pos, id3header, sizeof(id3header))

                    < (ssize_t)sizeof(id3header)) {

            // If we can't even read these 10 bytes, we might as well bail out,

            // even if there _were_ 10 bytes of valid mp3 audio data...

                // If we can't even read these 10 bytes, we might as well bail

                // out, even if there _were_ 10 bytes of valid mp3 audio data...

                return false;

            }



        if (id3header[0] == 'I' && id3header[1] == 'D' && id3header[2] == '3') {

            if (memcmp("ID3", id3header, 3)) {

                break;

            }



            // Skip the ID3v2 header.



            size_t len =
@@ -331,50 +335,30 @@ static bool Resync( 
            len += 10;



            *inout_pos += len;



            LOGV("skipped ID3 tag, new starting offset is %ld (0x%08lx)",

                 *inout_pos, *inout_pos);

        }

    }



    const size_t kMaxFrameSize = 4096;

    uint8_t *buffer = new uint8_t[kMaxFrameSize];



    off_t pos = *inout_pos - kMaxFrameSize;

    size_t buffer_offset = kMaxFrameSize;

    size_t buffer_length = kMaxFrameSize;

    off_t pos = *inout_pos;

    bool valid = false;

    do {

        if (buffer_offset + 3 >= buffer_length) {

            if (buffer_length < kMaxFrameSize) {

                break;

            }



            pos += buffer_offset;



        if (pos >= *inout_pos + 128 * 1024) {

            // Don't scan forever.

            LOGV("giving up at offset %ld", pos);

            break;

        }



            memmove(buffer, &buffer[buffer_offset], buffer_length - buffer_offset);

            buffer_length = buffer_length - buffer_offset;

            buffer_offset = 0;



            ssize_t n = source->readAt(

                    pos, &buffer[buffer_length], kMaxFrameSize - buffer_length);



            if (n <= 0) {

        uint8_t tmp[4];

        if (source->readAt(pos, tmp, 4) != 4) {

            break;

        }



            buffer_length += (size_t)n;



            continue;

        }



        uint32_t header = U32_AT(&buffer[buffer_offset]);

        uint32_t header = U32_AT(tmp);



        if (match_header != 0 && (header & kMask) != (match_header & kMask)) {

            ++buffer_offset;

            ++pos;

            continue;

        }
@@ -382,16 +366,16 @@ static bool Resync( 
        int sample_rate, num_channels, bitrate;

        if (!get_mp3_frame_size(header, &frame_size,

                               &sample_rate, &num_channels, &bitrate)) {

            ++buffer_offset;

            ++pos;

            continue;

        }



        LOGV("found possible 1st frame at %ld", pos + buffer_offset);

        LOGV("found possible 1st frame at %ld (header = 0x%08x)", pos, header);



        // We found what looks like a valid frame,

        // now find its successors.



        off_t test_pos = pos + buffer_offset + frame_size;

        off_t test_pos = pos + frame_size;



        valid = true;

        for (int j = 0; j < 3; ++j) {
@@ -422,7 +406,7 @@ static bool Resync( 
        }



        if (valid) {

            *inout_pos = pos + buffer_offset;

            *inout_pos = pos;



            if (out_header != NULL) {

                *out_header = header;
@@ -431,13 +415,9 @@ static bool Resync( 
            LOGV("no dice, no valid sequence of frames found.");

        }



        ++buffer_offset;



        ++pos;

    } while (!valid);



    delete[] buffer;

    buffer = NULL;



    return valid;

}