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codecparsers: h264: fix rbsp_more_data() implementation.
Account for trailing zero bits when checking for rbsp_more_data(). In particular, fix an hypothetical stream whereby rbsp_more_data() is called in the following conditions for PPS header: NalReader reached position 20, 12 bits are remaining and trailing data at current byte position is c8 00. rbsp_more_data() used to return TRUE whereas it should obviously return FALSE because x8 00 represents a valid rbsp_trailing_bits() structure. https://bugzilla.gnome.org/show_bug.cgi?id=685890 Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
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21b897de2f
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1 changed files with 28 additions and 19 deletions
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@ -253,33 +253,42 @@ nal_reader_is_byte_aligned (NalReader * nr)
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gboolean
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nal_reader_has_more_data (NalReader * nr)
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{
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guint remaining;
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NalReader nr_tmp;
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guint remaining, nbits;
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guint8 rbsp_stop_one_bit, zero_bits;
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remaining = nal_reader_get_remaining (nr);
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if (remaining == 0)
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return FALSE;
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if (remaining <= 8) {
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guint8 rbsp_stop_one_bit;
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nr_tmp = *nr;
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nr = &nr_tmp;
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if (!nal_reader_peek_bits_uint8 (nr, &rbsp_stop_one_bit, 1))
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/* The spec defines that more_rbsp_data() searches for the last bit
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equal to 1, and that it is the rbsp_stop_one_bit. Subsequent bits
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until byte boundary is reached shall be zero.
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This means that more_rbsp_data() is FALSE if the next bit is 1
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and the remaining bits until byte boundary are zero. One way to
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be sure that this bit was the very last one, is that every other
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bit after we reached byte boundary are also set to zero.
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Otherwise, if the next bit is 0 or if there are non-zero bits
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afterwards, then then we have more_rbsp_data() */
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if (!nal_reader_get_bits_uint8 (nr, &rbsp_stop_one_bit, 1))
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return FALSE;
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if (!rbsp_stop_one_bit)
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return TRUE;
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nbits = --remaining % 8;
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while (remaining > 0) {
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if (!nal_reader_get_bits_uint8 (nr, &zero_bits, nbits))
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return FALSE;
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if (rbsp_stop_one_bit == 1) {
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guint8 zero_bits;
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if (remaining == 1)
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return FALSE;
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if (!nal_reader_peek_bits_uint8 (nr, &zero_bits, remaining))
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return FALSE;
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if ((zero_bits - (1 << (remaining - 1))) == 0)
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return FALSE;
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}
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if (zero_bits != 0)
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return TRUE;
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remaining -= nbits;
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nbits = 8;
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}
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return TRUE;
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return FALSE;
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}
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/*********** end of nal parser ***************/
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