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Fix image corruption bug where the DC levels where not being reset correctly on decoding

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This commit is contained in:
Philip Heron 2018-06-27 08:45:07 +01:00
parent 0851b24b7c
commit 5c7dde620c
2 changed files with 15 additions and 4 deletions
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16
ssdv.c
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@ -588,6 +588,7 @@ static char ssdv_process(ssdv_t *s)
{
s->mcupart = 0;
s->mcu_id++;
s->reset_mcu = s->next_reset_mcu;
/* Test for the end of image */
if(s->mcu_id >= s->mcu_count)
@ -603,13 +604,15 @@ static char ssdv_process(ssdv_t *s)
/* The first MCU of each packet should be byte aligned */
ssdv_outbits_sync(s);
s->reset_mcu = s->mcu_id;
s->next_reset_mcu = s->reset_mcu = s->mcu_id;
s->packet_mcu_id = s->mcu_id;
s->packet_mcu_offset = s->pkt_size_payload - s->out_len;
}
if(s->mode == S_DECODING && s->mcu_id == s->reset_mcu)
{
s->workbits = s->worklen = 0;
}
/* Test for a reset marker */
if(s->dri > 0 && s->mcu_id > 0 && s->mcu_id % s->dri == 0)
@ -1029,8 +1032,9 @@ char ssdv_enc_get_packet(ssdv_t *s)
if(r == SSDV_BUFFER_FULL || r == SSDV_EOI)
{
uint16_t mcu_id = s->packet_mcu_id;
uint8_t i, mcu_offset = s->packet_mcu_offset;
uint8_t mcu_offset = s->packet_mcu_offset;
uint32_t x;
uint8_t i;
if(mcu_offset != 0xFF && mcu_offset >= s->pkt_size_payload)
{
@ -1251,7 +1255,13 @@ char ssdv_dec_feed(ssdv_t *s, uint8_t *packet)
s->packet_mcu_offset = packet[12];
s->packet_mcu_id = (packet[13] << 8) | packet[14];
if(s->packet_mcu_id != 0xFFFF) s->reset_mcu = s->packet_mcu_id;
if(s->packet_mcu_id != 0xFFFF)
{
/* Set the next reset MCU ID. We can't set it
* directly here as the previous MCU may still
* be being processed. */
s->next_reset_mcu = s->packet_mcu_id;
}
/* If this is the first packet, write the JPEG headers */
if(s->packet_id == 0)

1
ssdv.h
View file

@ -114,6 +114,7 @@ typedef struct
S_DECODING,
} mode;
uint32_t reset_mcu; /* MCU block to do absolute encoding */
uint32_t next_reset_mcu;
char needbits; /* Number of bits needed to decode integer */
/* The input huffman and quantisation tables */