libavcodec/mlpdec.c:990: error: Null Dereference
  pointer `&gb->buffer` last assigned on line 968 could be null and is dereferenced by call to `get_bits1()` at line 990, column 29.

libavcodec/mlpdec.c:945:1: start of procedure read_access_unit()
943.  *  otherwise the number of bytes consumed. */
944. 
945. static int read_access_unit(AVCodecContext *avctx, void* data, int *data_size,
     ^
946.                             AVPacket *avpkt)
947. {

libavcodec/mlpdec.c:948:5: 
946.                             AVPacket *avpkt)
947. {
948.     const uint8_t *buf = avpkt->data;
         ^
949.     int buf_size = avpkt->size;
950.     MLPDecodeContext *m = avctx->priv_data;

libavcodec/mlpdec.c:949:5: 
947. {
948.     const uint8_t *buf = avpkt->data;
949.     int buf_size = avpkt->size;
         ^
950.     MLPDecodeContext *m = avctx->priv_data;
951.     GetBitContext gb;

libavcodec/mlpdec.c:950:5: 
948.     const uint8_t *buf = avpkt->data;
949.     int buf_size = avpkt->size;
950.     MLPDecodeContext *m = avctx->priv_data;
         ^
951.     GetBitContext gb;
952.     unsigned int length, substr;

libavcodec/mlpdec.c:954:5: 
952.     unsigned int length, substr;
953.     unsigned int substream_start;
954.     unsigned int header_size = 4;
         ^
955.     unsigned int substr_header_size = 0;
956.     uint8_t substream_parity_present[MAX_SUBSTREAMS];

libavcodec/mlpdec.c:955:5: 
953.     unsigned int substream_start;
954.     unsigned int header_size = 4;
955.     unsigned int substr_header_size = 0;
         ^
956.     uint8_t substream_parity_present[MAX_SUBSTREAMS];
957.     uint16_t substream_data_len[MAX_SUBSTREAMS];

libavcodec/mlpdec.c:960:9: Taking false branch
958.     uint8_t parity_bits;
959. 
960.     if (buf_size < 4)
             ^
961.         return 0;
962. 

libavcodec/mlpdec.c:963:5: 
961.         return 0;
962. 
963.     length = (AV_RB16(buf) & 0xfff) * 2;
         ^
964. 
965.     if (length < 4 || length > buf_size)

libavutil/bswap.h:52:1: start of procedure bswap_16()
  50. 
  51. #ifndef bswap_16
  52. static av_always_inline av_const uint16_t bswap_16(uint16_t x)
      ^
  53. {
  54.     x= (x>>8) | (x<<8);

libavutil/bswap.h:54:5: 
  52. static av_always_inline av_const uint16_t bswap_16(uint16_t x)
  53. {
  54.     x= (x>>8) | (x<<8);
          ^
  55.     return x;
  56. }

libavutil/bswap.h:55:5: 
  53. {
  54.     x= (x>>8) | (x<<8);
  55.     return x;
          ^
  56. }
  57. #endif

libavutil/bswap.h:56:1: return from a call to bswap_16
  54.     x= (x>>8) | (x<<8);
  55.     return x;
  56. }
      ^
  57. #endif
  58. 

libavcodec/mlpdec.c:965:9: Taking false branch
963.     length = (AV_RB16(buf) & 0xfff) * 2;
964. 
965.     if (length < 4 || length > buf_size)
             ^
966.         return -1;
967. 

libavcodec/mlpdec.c:965:23: Taking false branch
963.     length = (AV_RB16(buf) & 0xfff) * 2;
964. 
965.     if (length < 4 || length > buf_size)
                           ^
966.         return -1;
967. 

libavcodec/mlpdec.c:968:5: 
966.         return -1;
967. 
968.     init_get_bits(&gb, (buf + 4), (length - 4) * 8);
         ^
969. 
970.     m->is_major_sync_unit = 0;

libavcodec/get_bits.h:473:1: start of procedure init_get_bits()
  471.  * responsible for checking for the buffer end yourself (take advantage of the padding)!
  472.  */
  473. static inline void init_get_bits(GetBitContext *s,
       ^
  474.                    const uint8_t *buffer, int bit_size)
  475. {

libavcodec/get_bits.h:476:5: 
  474.                    const uint8_t *buffer, int bit_size)
  475. {
  476.     int buffer_size= (bit_size+7)>>3;
           ^
  477.     if(buffer_size < 0 || bit_size < 0) {
  478.         buffer_size = bit_size = 0;

libavcodec/get_bits.h:477:8: Taking true branch
  475. {
  476.     int buffer_size= (bit_size+7)>>3;
  477.     if(buffer_size < 0 || bit_size < 0) {
              ^
  478.         buffer_size = bit_size = 0;
  479.         buffer = NULL;

libavcodec/get_bits.h:478:9: 
  476.     int buffer_size= (bit_size+7)>>3;
  477.     if(buffer_size < 0 || bit_size < 0) {
  478.         buffer_size = bit_size = 0;
               ^
  479.         buffer = NULL;
  480.     }

libavcodec/get_bits.h:479:9: 
  477.     if(buffer_size < 0 || bit_size < 0) {
  478.         buffer_size = bit_size = 0;
  479.         buffer = NULL;
               ^
  480.     }
  481. 

libavcodec/get_bits.h:482:5: 
  480.     }
  481. 
  482.     s->buffer= buffer;
           ^
  483.     s->size_in_bits= bit_size;
  484.     s->buffer_end= buffer + buffer_size;

libavcodec/get_bits.h:483:5: 
  481. 
  482.     s->buffer= buffer;
  483.     s->size_in_bits= bit_size;
           ^
  484.     s->buffer_end= buffer + buffer_size;
  485. #ifdef ALT_BITSTREAM_READER

libavcodec/get_bits.h:484:5: 
  482.     s->buffer= buffer;
  483.     s->size_in_bits= bit_size;
  484.     s->buffer_end= buffer + buffer_size;
           ^
  485. #ifdef ALT_BITSTREAM_READER
  486.     s->index=0;

libavcodec/get_bits.h:486:5: 
  484.     s->buffer_end= buffer + buffer_size;
  485. #ifdef ALT_BITSTREAM_READER
  486.     s->index=0;
           ^
  487. #elif defined LIBMPEG2_BITSTREAM_READER
  488.     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));

libavcodec/get_bits.h:496:1: return from a call to init_get_bits
  494.     skip_bits_long(s, 0);
  495. #endif
  496. }
       ^
  497. 
  498. static inline void align_get_bits(GetBitContext *s)

libavcodec/mlpdec.c:970:5: 
968.     init_get_bits(&gb, (buf + 4), (length - 4) * 8);
969. 
970.     m->is_major_sync_unit = 0;
         ^
971.     if (show_bits_long(&gb, 31) == (0xf8726fba >> 1)) {
972.         if (read_major_sync(m, &gb) < 0)

libavcodec/mlpdec.c:971:9: 
969. 
970.     m->is_major_sync_unit = 0;
971.     if (show_bits_long(&gb, 31) == (0xf8726fba >> 1)) {
             ^
972.         if (read_major_sync(m, &gb) < 0)
973.             goto error;

libavcodec/get_bits.h:447:1: start of procedure show_bits_long()
  445.  * shows 0-32 bits.
  446.  */
  447. static inline unsigned int show_bits_long(GetBitContext *s, int n){
       ^
  448.     if(n<=MIN_CACHE_BITS) return show_bits(s, n);
  449.     else{

libavcodec/get_bits.h:448:8: Taking false branch
  446.  */
  447. static inline unsigned int show_bits_long(GetBitContext *s, int n){
  448.     if(n<=MIN_CACHE_BITS) return show_bits(s, n);
              ^
  449.     else{
  450.         GetBitContext gb= *s;

libavcodec/get_bits.h:450:9: 
  448.     if(n<=MIN_CACHE_BITS) return show_bits(s, n);
  449.     else{
  450.         GetBitContext gb= *s;
               ^
  451.         return get_bits_long(&gb, n);
  452.     }

libavcodec/get_bits.h:451:9: 
  449.     else{
  450.         GetBitContext gb= *s;
  451.         return get_bits_long(&gb, n);
               ^
  452.     }
  453. }

libavcodec/get_bits.h:424:1: start of procedure get_bits_long()
    422.  * reads 0-32 bits.
    423.  */
    424. static inline unsigned int get_bits_long(GetBitContext *s, int n){
         ^
    425.     if(n<=MIN_CACHE_BITS) return get_bits(s, n);
    426.     else{

libavcodec/get_bits.h:425:8: Taking false branch
    423.  */
    424. static inline unsigned int get_bits_long(GetBitContext *s, int n){
    425.     if(n<=MIN_CACHE_BITS) return get_bits(s, n);
                ^
    426.     else{
    427. #ifdef ALT_BITSTREAM_READER_LE

libavcodec/get_bits.h:431:9: 
    429.         return ret | (get_bits(s, n-16) << 16);
    430. #else
    431.         int ret= get_bits(s, 16) << (n-16);
                 ^
    432.         return ret | get_bits(s, n-16);
    433. #endif

libavcodec/get_bits.h:362:1: start of procedure get_bits()
      360.  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
      361.  */
      362. static inline unsigned int get_bits(GetBitContext *s, int n){
           ^
      363.     register int tmp;
      364.     OPEN_READER(re, s)

libavcodec/get_bits.h:364:5: 
      362. static inline unsigned int get_bits(GetBitContext *s, int n){
      363.     register int tmp;
      364.     OPEN_READER(re, s)
               ^
      365.     UPDATE_CACHE(re, s)
      366.     tmp= SHOW_UBITS(re, s, n);

libavcodec/get_bits.h:365:5: 
      363.     register int tmp;
      364.     OPEN_READER(re, s)
      365.     UPDATE_CACHE(re, s)
               ^
      366.     tmp= SHOW_UBITS(re, s, n);
      367.     LAST_SKIP_BITS(re, s, n)

libavutil/bswap.h:60:1: start of procedure bswap_32()
        58. 
        59. #ifndef bswap_32
        60. static av_always_inline av_const uint32_t bswap_32(uint32_t x)
            ^
        61. {
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);

libavutil/bswap.h:62:5: 
        60. static av_always_inline av_const uint32_t bswap_32(uint32_t x)
        61. {
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
                ^
        63.     x= (x>>16) | (x<<16);
        64.     return x;

libavutil/bswap.h:63:5: 
        61. {
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
        63.     x= (x>>16) | (x<<16);
                ^
        64.     return x;
        65. }

libavutil/bswap.h:64:5: 
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
        63.     x= (x>>16) | (x<<16);
        64.     return x;
                ^
        65. }
        66. #endif

libavutil/bswap.h:65:1: return from a call to bswap_32
        63.     x= (x>>16) | (x<<16);
        64.     return x;
        65. }
            ^
        66. #endif
        67. 

libavcodec/get_bits.h:366:5: 
      364.     OPEN_READER(re, s)
      365.     UPDATE_CACHE(re, s)
      366.     tmp= SHOW_UBITS(re, s, n);
               ^
      367.     LAST_SKIP_BITS(re, s, n)
      368.     CLOSE_READER(re, s)

libavcodec/get_bits.h:367:5: 
      365.     UPDATE_CACHE(re, s)
      366.     tmp= SHOW_UBITS(re, s, n);
      367.     LAST_SKIP_BITS(re, s, n)
               ^
      368.     CLOSE_READER(re, s)
      369.     return tmp;

libavcodec/get_bits.h:368:5: 
      366.     tmp= SHOW_UBITS(re, s, n);
      367.     LAST_SKIP_BITS(re, s, n)
      368.     CLOSE_READER(re, s)
               ^
      369.     return tmp;
      370. }

libavcodec/get_bits.h:369:5: 
      367.     LAST_SKIP_BITS(re, s, n)
      368.     CLOSE_READER(re, s)
      369.     return tmp;
               ^
      370. }
      371. 

libavcodec/get_bits.h:370:1: return from a call to get_bits
      368.     CLOSE_READER(re, s)
      369.     return tmp;
      370. }
           ^
      371. 
      372. /**

libavcodec/get_bits.h:432:9: 
    430. #else
    431.         int ret= get_bits(s, 16) << (n-16);
    432.         return ret | get_bits(s, n-16);
                 ^
    433. #endif
    434.     }

libavcodec/get_bits.h:362:1: start of procedure get_bits()
      360.  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
      361.  */
      362. static inline unsigned int get_bits(GetBitContext *s, int n){
           ^
      363.     register int tmp;
      364.     OPEN_READER(re, s)

libavcodec/get_bits.h:364:5: 
      362. static inline unsigned int get_bits(GetBitContext *s, int n){
      363.     register int tmp;
      364.     OPEN_READER(re, s)
               ^
      365.     UPDATE_CACHE(re, s)
      366.     tmp= SHOW_UBITS(re, s, n);

libavcodec/get_bits.h:365:5: 
      363.     register int tmp;
      364.     OPEN_READER(re, s)
      365.     UPDATE_CACHE(re, s)
               ^
      366.     tmp= SHOW_UBITS(re, s, n);
      367.     LAST_SKIP_BITS(re, s, n)

libavutil/bswap.h:60:1: start of procedure bswap_32()
        58. 
        59. #ifndef bswap_32
        60. static av_always_inline av_const uint32_t bswap_32(uint32_t x)
            ^
        61. {
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);

libavutil/bswap.h:62:5: 
        60. static av_always_inline av_const uint32_t bswap_32(uint32_t x)
        61. {
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
                ^
        63.     x= (x>>16) | (x<<16);
        64.     return x;

libavutil/bswap.h:63:5: 
        61. {
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
        63.     x= (x>>16) | (x<<16);
                ^
        64.     return x;
        65. }

libavutil/bswap.h:64:5: 
        62.     x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
        63.     x= (x>>16) | (x<<16);
        64.     return x;
                ^
        65. }
        66. #endif

libavutil/bswap.h:65:1: return from a call to bswap_32
        63.     x= (x>>16) | (x<<16);
        64.     return x;
        65. }
            ^
        66. #endif
        67. 

libavcodec/get_bits.h:366:5: 
      364.     OPEN_READER(re, s)
      365.     UPDATE_CACHE(re, s)
      366.     tmp= SHOW_UBITS(re, s, n);
               ^
      367.     LAST_SKIP_BITS(re, s, n)
      368.     CLOSE_READER(re, s)

libavcodec/get_bits.h:367:5: 
      365.     UPDATE_CACHE(re, s)
      366.     tmp= SHOW_UBITS(re, s, n);
      367.     LAST_SKIP_BITS(re, s, n)
               ^
      368.     CLOSE_READER(re, s)
      369.     return tmp;

libavcodec/get_bits.h:368:5: 
      366.     tmp= SHOW_UBITS(re, s, n);
      367.     LAST_SKIP_BITS(re, s, n)
      368.     CLOSE_READER(re, s)
               ^
      369.     return tmp;
      370. }

libavcodec/get_bits.h:369:5: 
      367.     LAST_SKIP_BITS(re, s, n)
      368.     CLOSE_READER(re, s)
      369.     return tmp;
               ^
      370. }
      371. 

libavcodec/get_bits.h:370:1: return from a call to get_bits
      368.     CLOSE_READER(re, s)
      369.     return tmp;
      370. }
           ^
      371. 
      372. /**

libavcodec/get_bits.h:435:1: return from a call to get_bits_long
    433. #endif
    434.     }
    435. }
         ^
    436. 
    437. /**

libavcodec/get_bits.h:453:1: return from a call to show_bits_long
  451.         return get_bits_long(&gb, n);
  452.     }
  453. }
       ^
  454. 
  455. static inline int check_marker(GetBitContext *s, const char *msg)

libavcodec/mlpdec.c:971:9: Taking false branch
969. 
970.     m->is_major_sync_unit = 0;
971.     if (show_bits_long(&gb, 31) == (0xf8726fba >> 1)) {
             ^
972.         if (read_major_sync(m, &gb) < 0)
973.             goto error;

libavcodec/mlpdec.c:978:10: Taking false branch
976.     }
977. 
978.     if (!m->params_valid) {
              ^
979.         av_log(m->avctx, AV_LOG_WARNING,
980.                "Stream parameters not seen; skipping frame.\n");

libavcodec/mlpdec.c:985:5: 
983.     }
984. 
985.     substream_start = 0;
         ^
986. 
987.     for (substr = 0; substr < m->num_substreams; substr++) {

libavcodec/mlpdec.c:987:10: 
985.     substream_start = 0;
986. 
987.     for (substr = 0; substr < m->num_substreams; substr++) {
              ^
988.         int extraword_present, checkdata_present, end, nonrestart_substr;
989. 

libavcodec/mlpdec.c:987:22: Loop condition is true. Entering loop body
985.     substream_start = 0;
986. 
987.     for (substr = 0; substr < m->num_substreams; substr++) {
                          ^
988.         int extraword_present, checkdata_present, end, nonrestart_substr;
989. 

libavcodec/mlpdec.c:990:9: 
988.         int extraword_present, checkdata_present, end, nonrestart_substr;
989. 
990.         extraword_present = get_bits1(&gb);
             ^
991.         nonrestart_substr = get_bits1(&gb);
992.         checkdata_present = get_bits1(&gb);

libavcodec/get_bits.h:393:1: start of procedure get_bits1()
  391. }
  392. 
  393. static inline unsigned int get_bits1(GetBitContext *s){
       ^
  394. #ifdef ALT_BITSTREAM_READER
  395.     unsigned int index= s->index;

libavcodec/get_bits.h:395:5: 
  393. static inline unsigned int get_bits1(GetBitContext *s){
  394. #ifdef ALT_BITSTREAM_READER
  395.     unsigned int index= s->index;
           ^
  396.     uint8_t result= s->buffer[ index>>3 ];
  397. #ifdef ALT_BITSTREAM_READER_LE

libavcodec/get_bits.h:396:5: 
  394. #ifdef ALT_BITSTREAM_READER
  395.     unsigned int index= s->index;
  396.     uint8_t result= s->buffer[ index>>3 ];
           ^
  397. #ifdef ALT_BITSTREAM_READER_LE
  398.     result>>= (index&0x07);

static int read_access_unit(AVCodecContext *avctx, void* data, int *data_size,
                            AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    MLPDecodeContext *m = avctx->priv_data;
    GetBitContext gb;
    unsigned int length, substr;
    unsigned int substream_start;
    unsigned int header_size = 4;
    unsigned int substr_header_size = 0;
    uint8_t substream_parity_present[MAX_SUBSTREAMS];
    uint16_t substream_data_len[MAX_SUBSTREAMS];
    uint8_t parity_bits;
    if (buf_size < 4)
        return 0;
    length = (AV_RB16(buf) & 0xfff) * 2;
    if (length < 4 || length > buf_size)
        return -1;
    init_get_bits(&gb, (buf + 4), (length - 4) * 8);
    m->is_major_sync_unit = 0;
    if (show_bits_long(&gb, 31) == (0xf8726fba >> 1)) {
        if (read_major_sync(m, &gb) < 0)
            goto error;
        m->is_major_sync_unit = 1;
        header_size += 28;
    }
    if (!m->params_valid) {
        av_log(m->avctx, AV_LOG_WARNING,
               "Stream parameters not seen; skipping frame.\n");
        *data_size = 0;
        return length;
    }
    substream_start = 0;
    for (substr = 0; substr < m->num_substreams; substr++) {
        int extraword_present, checkdata_present, end, nonrestart_substr;
        extraword_present = get_bits1(&gb);
        nonrestart_substr = get_bits1(&gb);
        checkdata_present = get_bits1(&gb);
        skip_bits1(&gb);
        end = get_bits(&gb, 12) * 2;
        substr_header_size += 2;
        if (extraword_present) {
            if (m->avctx->codec_id == CODEC_ID_MLP) {
                av_log(m->avctx, AV_LOG_ERROR, "There must be no extraword for MLP.\n");
                goto error;
            }
            skip_bits(&gb, 16);
            substr_header_size += 2;
        }
        if (!(nonrestart_substr ^ m->is_major_sync_unit)) {
            av_log(m->avctx, AV_LOG_ERROR, "Invalid nonrestart_substr.\n");
            goto error;
        }
        if (end + header_size + substr_header_size > length) {
            av_log(m->avctx, AV_LOG_ERROR,
                   "Indicated length of substream %d data goes off end of "
                   "packet.\n", substr);
            end = length - header_size - substr_header_size;
        }
        if (end < substream_start) {
            av_log(avctx, AV_LOG_ERROR,
                   "Indicated end offset of substream %d data "
                   "is smaller than calculated start offset.\n",
                   substr);
            goto error;
        }
        if (substr > m->max_decoded_substream)
            continue;
        substream_parity_present[substr] = checkdata_present;
        substream_data_len[substr] = end - substream_start;
        substream_start = end;
    }
    parity_bits  = ff_mlp_calculate_parity(buf, 4);
    parity_bits ^= ff_mlp_calculate_parity(buf + header_size, substr_header_size);
    if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
        av_log(avctx, AV_LOG_ERROR, "Parity check failed.\n");
        goto error;
    }
    buf += header_size + substr_header_size;
    for (substr = 0; substr <= m->max_decoded_substream; substr++) {
        SubStream *s = &m->substream[substr];
        init_get_bits(&gb, buf, substream_data_len[substr] * 8);
        m->matrix_changed = 0;
        memset(m->filter_changed, 0, sizeof(m->filter_changed));
        s->blockpos = 0;
        do {
            if (get_bits1(&gb)) {
                if (get_bits1(&gb)) {
                    if (read_restart_header(m, &gb, buf, substr) < 0)
                        goto next_substr;
                    s->restart_seen = 1;
                }
                if (!s->restart_seen)
                    goto next_substr;
                if (read_decoding_params(m, &gb, substr) < 0)
                    goto next_substr;
            }
            if (!s->restart_seen)
                goto next_substr;
            if (read_block_data(m, &gb, substr) < 0)
                return -1;
            if (get_bits_count(&gb) >= substream_data_len[substr] * 8)
                goto substream_length_mismatch;
        } while (!get_bits1(&gb));
        skip_bits(&gb, (-get_bits_count(&gb)) & 15);
        if (substream_data_len[substr] * 8 - get_bits_count(&gb) >= 32) {
            int shorten_by;
            if (get_bits(&gb, 16) != 0xD234)
                return -1;
            shorten_by = get_bits(&gb, 16);
            if      (m->avctx->codec_id == CODEC_ID_TRUEHD && shorten_by  & 0x2000)
                s->blockpos -= FFMIN(shorten_by & 0x1FFF, s->blockpos);
            else if (m->avctx->codec_id == CODEC_ID_MLP    && shorten_by != 0xD234)
                return -1;
            if (substr == m->max_decoded_substream)
                av_log(m->avctx, AV_LOG_INFO, "End of stream indicated.\n");
        }
        if (substream_parity_present[substr]) {
            uint8_t parity, checksum;
            if (substream_data_len[substr] * 8 - get_bits_count(&gb) != 16)
                goto substream_length_mismatch;
            parity   = ff_mlp_calculate_parity(buf, substream_data_len[substr] - 2);
            checksum = ff_mlp_checksum8       (buf, substream_data_len[substr] - 2);
            if ((get_bits(&gb, 8) ^ parity) != 0xa9    )
                av_log(m->avctx, AV_LOG_ERROR, "Substream %d parity check failed.\n", substr);
            if ( get_bits(&gb, 8)           != checksum)
                av_log(m->avctx, AV_LOG_ERROR, "Substream %d checksum failed.\n"    , substr);
        }
        if (substream_data_len[substr] * 8 != get_bits_count(&gb))
            goto substream_length_mismatch;
next_substr:
        if (!s->restart_seen)
            av_log(m->avctx, AV_LOG_ERROR,
                   "No restart header present in substream %d.\n", substr);
        buf += substream_data_len[substr];
    }
    rematrix_channels(m, m->max_decoded_substream);
    if (output_data(m, m->max_decoded_substream, data, data_size) < 0)
        return -1;
    return length;
substream_length_mismatch:
    av_log(m->avctx, AV_LOG_ERROR, "substream %d length mismatch\n", substr);
    return -1;
error:
    m->params_valid = 0;
    return -1;
}
['static int read_access_unit(AVCodecContext *avctx, void* data, int *data_size,\n                            AVPacket *avpkt)\n{\n    const uint8_t *buf = avpkt->data;\n    int buf_size = avpkt->size;\n    MLPDecodeContext *m = avctx->priv_data;\n    GetBitContext gb;\n    unsigned int length, substr;\n    unsigned int substream_start;\n    unsigned int header_size = 4;\n    unsigned int substr_header_size = 0;\n    uint8_t substream_parity_present[MAX_SUBSTREAMS];\n    uint16_t substream_data_len[MAX_SUBSTREAMS];\n    uint8_t parity_bits;\n    if (buf_size < 4)\n        return 0;\n    length = (AV_RB16(buf) & 0xfff) * 2;\n    if (length < 4 || length > buf_size)\n        return -1;\n    init_get_bits(&gb, (buf + 4), (length - 4) * 8);\n    m->is_major_sync_unit = 0;\n    if (show_bits_long(&gb, 31) == (0xf8726fba >> 1)) {\n        if (read_major_sync(m, &gb) < 0)\n            goto error;\n        m->is_major_sync_unit = 1;\n        header_size += 28;\n    }\n    if (!m->params_valid) {\n        av_log(m->avctx, AV_LOG_WARNING,\n               "Stream parameters not seen; skipping frame.\\n");\n        *data_size = 0;\n        return length;\n    }\n    substream_start = 0;\n    for (substr = 0; substr < m->num_substreams; substr++) {\n        int extraword_present, checkdata_present, end, nonrestart_substr;\n        extraword_present = get_bits1(&gb);\n        nonrestart_substr = get_bits1(&gb);\n        checkdata_present = get_bits1(&gb);\n        skip_bits1(&gb);\n        end = get_bits(&gb, 12) * 2;\n        substr_header_size += 2;\n        if (extraword_present) {\n            if (m->avctx->codec_id == CODEC_ID_MLP) {\n                av_log(m->avctx, AV_LOG_ERROR, "There must be no extraword for MLP.\\n");\n                goto error;\n            }\n            skip_bits(&gb, 16);\n            substr_header_size += 2;\n        }\n        if (!(nonrestart_substr ^ m->is_major_sync_unit)) {\n            av_log(m->avctx, AV_LOG_ERROR, "Invalid nonrestart_substr.\\n");\n            goto error;\n        }\n        if (end + header_size + substr_header_size > length) {\n            av_log(m->avctx, AV_LOG_ERROR,\n                   "Indicated length of substream %d data goes off end of "\n                   "packet.\\n", substr);\n            end = length - header_size - substr_header_size;\n        }\n        if (end < substream_start) {\n            av_log(avctx, AV_LOG_ERROR,\n                   "Indicated end offset of substream %d data "\n                   "is smaller than calculated start offset.\\n",\n                   substr);\n            goto error;\n        }\n        if (substr > m->max_decoded_substream)\n            continue;\n        substream_parity_present[substr] = checkdata_present;\n        substream_data_len[substr] = end - substream_start;\n        substream_start = end;\n    }\n    parity_bits  = ff_mlp_calculate_parity(buf, 4);\n    parity_bits ^= ff_mlp_calculate_parity(buf + header_size, substr_header_size);\n    if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {\n        av_log(avctx, AV_LOG_ERROR, "Parity check failed.\\n");\n        goto error;\n    }\n    buf += header_size + substr_header_size;\n    for (substr = 0; substr <= m->max_decoded_substream; substr++) {\n        SubStream *s = &m->substream[substr];\n        init_get_bits(&gb, buf, substream_data_len[substr] * 8);\n        m->matrix_changed = 0;\n        memset(m->filter_changed, 0, sizeof(m->filter_changed));\n        s->blockpos = 0;\n        do {\n            if (get_bits1(&gb)) {\n                if (get_bits1(&gb)) {\n                    if (read_restart_header(m, &gb, buf, substr) < 0)\n                        goto next_substr;\n                    s->restart_seen = 1;\n                }\n                if (!s->restart_seen)\n                    goto next_substr;\n                if (read_decoding_params(m, &gb, substr) < 0)\n                    goto next_substr;\n            }\n            if (!s->restart_seen)\n                goto next_substr;\n            if (read_block_data(m, &gb, substr) < 0)\n                return -1;\n            if (get_bits_count(&gb) >= substream_data_len[substr] * 8)\n                goto substream_length_mismatch;\n        } while (!get_bits1(&gb));\n        skip_bits(&gb, (-get_bits_count(&gb)) & 15);\n        if (substream_data_len[substr] * 8 - get_bits_count(&gb) >= 32) {\n            int shorten_by;\n            if (get_bits(&gb, 16) != 0xD234)\n                return -1;\n            shorten_by = get_bits(&gb, 16);\n            if      (m->avctx->codec_id == CODEC_ID_TRUEHD && shorten_by  & 0x2000)\n                s->blockpos -= FFMIN(shorten_by & 0x1FFF, s->blockpos);\n            else if (m->avctx->codec_id == CODEC_ID_MLP    && shorten_by != 0xD234)\n                return -1;\n            if (substr == m->max_decoded_substream)\n                av_log(m->avctx, AV_LOG_INFO, "End of stream indicated.\\n");\n        }\n        if (substream_parity_present[substr]) {\n            uint8_t parity, checksum;\n            if (substream_data_len[substr] * 8 - get_bits_count(&gb) != 16)\n                goto substream_length_mismatch;\n            parity   = ff_mlp_calculate_parity(buf, substream_data_len[substr] - 2);\n            checksum = ff_mlp_checksum8       (buf, substream_data_len[substr] - 2);\n            if ((get_bits(&gb, 8) ^ parity) != 0xa9    )\n                av_log(m->avctx, AV_LOG_ERROR, "Substream %d parity check failed.\\n", substr);\n            if ( get_bits(&gb, 8)           != checksum)\n                av_log(m->avctx, AV_LOG_ERROR, "Substream %d checksum failed.\\n"    , substr);\n        }\n        if (substream_data_len[substr] * 8 != get_bits_count(&gb))\n            goto substream_length_mismatch;\nnext_substr:\n        if (!s->restart_seen)\n            av_log(m->avctx, AV_LOG_ERROR,\n                   "No restart header present in substream %d.\\n", substr);\n        buf += substream_data_len[substr];\n    }\n    rematrix_channels(m, m->max_decoded_substream);\n    if (output_data(m, m->max_decoded_substream, data, data_size) < 0)\n        return -1;\n    return length;\nsubstream_length_mismatch:\n    av_log(m->avctx, AV_LOG_ERROR, "substream %d length mismatch\\n", substr);\n    return -1;\nerror:\n    m->params_valid = 0;\n    return -1;\n}', 'static av_always_inline av_const uint16_t bswap_16(uint16_t x)\n{\n    x= (x>>8) | (x<<8);\n    return x;\n}', 'static inline void init_get_bits(GetBitContext *s,\n                   const uint8_t *buffer, int bit_size)\n{\n    int buffer_size= (bit_size+7)>>3;\n    if(buffer_size < 0 || bit_size < 0) {\n        buffer_size = bit_size = 0;\n        buffer = NULL;\n    }\n    s->buffer= buffer;\n    s->size_in_bits= bit_size;\n    s->buffer_end= buffer + buffer_size;\n#ifdef ALT_BITSTREAM_READER\n    s->index=0;\n#elif defined LIBMPEG2_BITSTREAM_READER\n    s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));\n    s->bit_count = 16 + 8*((intptr_t)buffer&1);\n    skip_bits_long(s, 0);\n#elif defined A32_BITSTREAM_READER\n    s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));\n    s->bit_count = 32 + 8*((intptr_t)buffer&3);\n    skip_bits_long(s, 0);\n#endif\n}', 'static inline unsigned int show_bits_long(GetBitContext *s, int n){\n    if(n<=MIN_CACHE_BITS) return show_bits(s, n);\n    else{\n        GetBitContext gb= *s;\n        return get_bits_long(&gb, n);\n    }\n}', 'static inline unsigned int get_bits_long(GetBitContext *s, int n){\n    if(n<=MIN_CACHE_BITS) return get_bits(s, n);\n    else{\n#ifdef ALT_BITSTREAM_READER_LE\n        int ret= get_bits(s, 16);\n        return ret | (get_bits(s, n-16) << 16);\n#else\n        int ret= get_bits(s, 16) << (n-16);\n        return ret | get_bits(s, n-16);\n#endif\n    }\n}', 'static inline unsigned int get_bits(GetBitContext *s, int n){\n    register int tmp;\n    OPEN_READER(re, s)\n    UPDATE_CACHE(re, s)\n    tmp= SHOW_UBITS(re, s, n);\n    LAST_SKIP_BITS(re, s, n)\n    CLOSE_READER(re, s)\n    return tmp;\n}', 'static av_always_inline av_const uint32_t bswap_32(uint32_t x)\n{\n    x= ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);\n    x= (x>>16) | (x<<16);\n    return x;\n}', 'static inline unsigned int get_bits1(GetBitContext *s){\n#ifdef ALT_BITSTREAM_READER\n    unsigned int index= s->index;\n    uint8_t result= s->buffer[ index>>3 ];\n#ifdef ALT_BITSTREAM_READER_LE\n    result>>= (index&0x07);\n    result&= 1;\n#else\n    result<<= (index&0x07);\n    result>>= 8 - 1;\n#endif\n    index++;\n    s->index= index;\n    return result;\n#else\n    return get_bits(s, 1);\n#endif\n}']