libavcodec/h261dec.c:296: error: Integer Overflow L2
  (2 - [`h->s.bc.bits_left`, `h->s.bc.bits_left` + 32]):unsigned32 by call to `bitstream_skip`.

libavcodec/h261dec.c:259:1: Parameter `h->s.bc.bits_left`
257.  * @return <0 if an error occurred
258.  */
259. static int h261_decode_block(H261Context *h, int16_t *block, int n, int coded)
     ^
260. {
261.     MpegEncContext *const s = &h->s;

libavcodec/h261dec.c:293:21: Call
291.         // 0    1       1s
292.         // *    *       0*
293.         int check = bitstream_peek(&s->bc, 2);
                         ^
294.         i = 0;
295.         if (check & 0x2) {

libavcodec/bitstream.h:215:1: Parameter `n`
  213. /* Return n bits from the buffer, but do not change the buffer state.
  214.  * n has to be in the 0-32 range. */
  215. static inline unsigned bitstream_peek(BitstreamContext *bc, unsigned n)
       ^
  216. {
  217.     if (n > bc->bits_left)

libavcodec/h261dec.c:296:13: Call
294.         i = 0;
295.         if (check & 0x2) {
296.             bitstream_skip(&s->bc, 2);
                 ^
297.             block[0] = (check & 0x1) ? -1 : 1;
298.             i        = 1;

libavcodec/bitstream.h:241:1: <LHS trace>
239. 
240. /* Skip n bits in the buffer. */
241. static inline void bitstream_skip(BitstreamContext *bc, unsigned n)
     ^
242. {
243.     if (n <= bc->bits_left)

libavcodec/bitstream.h:241:1: Parameter `n`
  239. 
  240. /* Skip n bits in the buffer. */
  241. static inline void bitstream_skip(BitstreamContext *bc, unsigned n)
       ^
  242. {
  243.     if (n <= bc->bits_left)

libavcodec/bitstream.h:241:1: <RHS trace>
239. 
240. /* Skip n bits in the buffer. */
241. static inline void bitstream_skip(BitstreamContext *bc, unsigned n)
     ^
242. {
243.     if (n <= bc->bits_left)

libavcodec/bitstream.h:241:1: Parameter `n`
  239. 
  240. /* Skip n bits in the buffer. */
  241. static inline void bitstream_skip(BitstreamContext *bc, unsigned n)
       ^
  242. {
  243.     if (n <= bc->bits_left)

libavcodec/bitstream.h:246:9: Binary operation: (2 - [h->s.bc.bits_left, h->s.bc.bits_left + 32]):unsigned32 by call to `bitstream_skip` 
  244.         skip_remaining(bc, n);
  245.     else {
  246.         n -= bc->bits_left;
               ^
  247.         skip_remaining(bc, bc->bits_left);
  248.         if (n >= 64) {

static inline void bitstream_skip(BitstreamContext *bc, unsigned n)
{
    if (n <= bc->bits_left)
        skip_remaining(bc, n);
    else {
        n -= bc->bits_left;
        skip_remaining(bc, bc->bits_left);
        if (n >= 64) {
            unsigned skip = n / 8;
            n -= skip * 8;
            bc->ptr += skip;
        }
        refill_64(bc);
        if (n)
            skip_remaining(bc, n);
    }
}
['static int h261_decode_block(H261Context *h, int16_t *block, int n, int coded)\n{\n    MpegEncContext *const s = &h->s;\n    int code, level, i, j, run;\n    RLTable *rl = &ff_h261_rl_tcoeff;\n    const uint8_t *scan_table;\n    scan_table = s->intra_scantable.permutated;\n    if (s->mb_intra) {\n        level = bitstream_read(&s->bc, 8);\n        if ((level & 0x7F) == 0) {\n            av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\\n",\n                   level, s->mb_x, s->mb_y);\n            return -1;\n        }\n        if (level == 255)\n            level = 128;\n        block[0] = level;\n        i        = 1;\n    } else if (coded) {\n        int check = bitstream_peek(&s->bc, 2);\n        i = 0;\n        if (check & 0x2) {\n            bitstream_skip(&s->bc, 2);\n            block[0] = (check & 0x1) ? -1 : 1;\n            i        = 1;\n        }\n    } else {\n        i = 0;\n    }\n    if (!coded) {\n        s->block_last_index[n] = i - 1;\n        return 0;\n    }\n    for (;;) {\n        code = bitstream_read_vlc(&s->bc, rl->vlc.table, TCOEFF_VLC_BITS, 2);\n        if (code < 0) {\n            av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\\n",\n                   s->mb_x, s->mb_y);\n            return -1;\n        }\n        if (code == rl->n) {\n            run   = bitstream_read(&s->bc, 6);\n            level = bitstream_read_signed(&s->bc, 8);\n        } else if (code == 0) {\n            break;\n        } else {\n            run   = rl->table_run[code];\n            level = rl->table_level[code];\n            if (bitstream_read_bit(&s->bc))\n                level = -level;\n        }\n        i += run;\n        if (i >= 64) {\n            av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\\n",\n                   s->mb_x, s->mb_y);\n            return -1;\n        }\n        j        = scan_table[i];\n        block[j] = level;\n        i++;\n    }\n    s->block_last_index[n] = i - 1;\n    return 0;\n}', 'static inline unsigned bitstream_peek(BitstreamContext *bc, unsigned n)\n{\n    if (n > bc->bits_left)\n        refill_32(bc);\n    return show_val(bc, n);\n}', 'static inline void bitstream_skip(BitstreamContext *bc, unsigned n)\n{\n    if (n <= bc->bits_left)\n        skip_remaining(bc, n);\n    else {\n        n -= bc->bits_left;\n        skip_remaining(bc, bc->bits_left);\n        if (n >= 64) {\n            unsigned skip = n / 8;\n            n -= skip * 8;\n            bc->ptr += skip;\n        }\n        refill_64(bc);\n        if (n)\n            skip_remaining(bc, n);\n    }\n}']