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avcodec/rangecoder: Add and test ff_rac_check_termination() 

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2018-12-23 14:17:11 +01:00
parent 20b10ba83c
commit b6c2c58904
3 changed files with 33 additions and 2 deletions
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19
libavcodec/rangecoder.c
View File

@ -121,3 +121,22 @@ int ff_rac_terminate(RangeCoder *c, int version)
return c->bytestream - c->bytestream_start;
}
int ff_rac_check_termination(RangeCoder *c, int version)
{
if (version == 1) {
RangeCoder tmp = *c;
get_rac(c, (uint8_t[]) { 129 });
if (c->bytestream == tmp.bytestream && c->bytestream > c->bytestream_start)
tmp.low -= *--tmp.bytestream;
tmp.bytestream_end = tmp.bytestream;
if (get_rac(&tmp, (uint8_t[]) { 129 }))
return AVERROR_INVALIDDATA;
} else {
if (c->bytestream_end != c->bytestream)
return AVERROR_INVALIDDATA;
}
return 0;
}

9
libavcodec/rangecoder.h
View File

@ -57,6 +57,15 @@ void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf, int buf_size);
*/
int ff_rac_terminate(RangeCoder *c, int version);
/**
* Check if at the current position there is a valid looking termination
* @param version version 0 requires the decoder to know the data size in bytes
* version 1 needs about 1 bit more space but does not need to
* carry the size from encoder to decoder
* @returns negative AVERROR code on error or non negative.
*/
int ff_rac_check_termination(RangeCoder *c, int version);
void ff_build_rac_states(RangeCoder *c, int factor, int max_p);
static inline void renorm_encoder(RangeCoder *c)

7
libavcodec/tests/rangecoder.c
View File

@ -60,8 +60,11 @@ int main(void)
av_log(NULL, AV_LOG_ERROR, "rac failure at %d pass %d version %d\n", i, p, version);
return 1;
}
if(version)
get_rac(&c, (uint8_t[]) { 129 });
if (ff_rac_check_termination(&c, version) < 0) {
av_log(NULL, AV_LOG_ERROR, "rac failure at termination pass %d version %d\n", p, version);
return 1;
}
if (c.bytestream - c.bytestream_start - actual_length != version) {
av_log(NULL, AV_LOG_ERROR, "rac failure at pass %d version %d\n", p, version);
return 1;