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Commit 9dec4911 authored by James Dong's avatar James Dong
Browse files

MP3Extractor and MP3 decoder fixes - DO NOT MERGE 

cherry-picked the following patches from HC branch:
o PV's mp3 decoder mistreated inputBufferCurrentLength in unit of bytes as in unit of bits
o Do not enforce the rule in MP3Extractor that all audio frames in an mp3 file must have the same mode
o When the temp buffer wraps around, the next read position should start
    from what have been read to avoid reading the same remaining bytes in
    the buffer again.
o Speed up MP3Extractor using cached reads

bug - 4083532

Change-Id: I7bbd2bd358fd5ee322287866cb8ee0c2bb217fea
parent 0ef63152

media/libstagefright/MP3Extractor.cpp

+43 −6
Original line number Diff line number Diff line
@@ -37,10 +37,10 @@ 
namespace android {



// Everything must match except for

// protection, bitrate, padding, private bits, mode extension,

// protection, bitrate, padding, private bits, mode, mode extension,

// copyright bit, original bit and emphasis.

// Yes ... there are things that must indeed match...

static const uint32_t kMask = 0xfffe0cc0;

static const uint32_t kMask = 0xfffe0c00;



static bool get_mp3_frame_size(

        uint32_t header, size_t *frame_size,
@@ -344,22 +344,55 @@ static bool Resync( 


    off_t pos = *inout_pos;

    bool valid = false;



    const size_t kMaxReadBytes = 1024;

    const off_t kMaxBytesChecked = 128 * 1024;

    uint8_t buf[kMaxReadBytes];

    ssize_t bytesToRead = kMaxReadBytes;

    ssize_t totalBytesRead = 0;

    ssize_t remainingBytes = 0;

    bool reachEOS = false;

    uint8_t *tmp = buf;



    do {

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

        if (pos >= *inout_pos + kMaxBytesChecked) {

            // Don't scan forever.

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

            break;

        }



        uint8_t tmp[4];

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

        if (remainingBytes < 4) {

            if (reachEOS) {

                break;

            } else {

                memcpy(buf, tmp, remainingBytes);

                bytesToRead = kMaxReadBytes - remainingBytes;



                /*

                 * The next read position should start from the end of

                 * the last buffer, and thus should include the remaining

                 * bytes in the buffer.

                 */

                totalBytesRead = source->readAt(pos + remainingBytes,

                                                buf + remainingBytes,

                                                bytesToRead);

                if (totalBytesRead <= 0) {

                    break;

                }

                reachEOS = (totalBytesRead != bytesToRead);

                totalBytesRead += remainingBytes;

                remainingBytes = totalBytesRead;

                tmp = buf;

                continue;

            }

        }



        uint32_t header = U32_AT(tmp);



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

            ++pos;

            ++tmp;

            --remainingBytes;

            continue;

        }
@@ -368,6 +401,8 @@ static bool Resync( 
        if (!get_mp3_frame_size(header, &frame_size,

                               &sample_rate, &num_channels, &bitrate)) {

            ++pos;

            ++tmp;

            --remainingBytes;

            continue;

        }
@@ -417,6 +452,8 @@ static bool Resync( 
        }



        ++pos;

        ++tmp;

        --remainingBytes;

    } while (!valid);



    return valid;

media/libstagefright/codecs/mp3dec/src/pvmp3_decode_header.cpp

+4 −2
Original line number Diff line number Diff line
@@ -122,8 +122,10 @@ ERROR_CODE pvmp3_decode_header(tmp3Bits *inputStream, 


    /*

     * Verify that at least the header is complete

     * Note that SYNC_WORD_LNGTH is in unit of bits, but inputBufferCurrentLength

     * is in unit of bytes.

     */

    if (inputStream->inputBufferCurrentLength < (SYNC_WORD_LNGTH + 21))

    if (inputStream->inputBufferCurrentLength < ((SYNC_WORD_LNGTH + 21) >> 3))

    {

        return NO_ENOUGH_MAIN_DATA_ERROR;

    }