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Optimize DTS calculation to fix linear access slowdown #22

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Optimize DTS calculation to fix linear access slowdown #22

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47 changes: 36 additions & 11 deletions core/timeline.c
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Original file line number Diff line number Diff line change
Expand Up @@ -407,20 +407,45 @@ static int isom_get_dts_from_info_list( isom_timeline_t *timeline, uint32_t samp
}
else
{
*dts = 0;
uint32_t distance = sample_number - 1;
lsmash_entry_t *entry;
for( entry = timeline->info_list->head; entry; entry = entry->next )
uint64_t dts_temp;
uint32_t start_num;
lsmash_entry_t* entry;
if( timeline->last_accessed_sample_number > 0 && sample_number > timeline->last_accessed_sample_number )
{
isom_sample_info_t *info = (isom_sample_info_t *)entry->data;
if( !info )
/* Forward scan from last accessed position. */
dts_temp = timeline->last_accessed_sample_dts;
start_num = timeline->last_accessed_sample_number;
entry = lsmash_list_get_entry(timeline->info_list, start_num);
if( !entry )
return LSMASH_ERR_NAMELESS;
if( distance-- == 0 )
break;
*dts += info->duration;
for( uint32_t i = start_num; i < sample_number; i++ )
{
isom_sample_info_t* info = (isom_sample_info_t*)entry->data;
if( !info )
return LSMASH_ERR_NAMELESS;
dts_temp += info->duration;
entry = entry->next;
if( !entry && i < sample_number - 1 )
return LSMASH_ERR_NAMELESS;
}
}
if( !entry )
return LSMASH_ERR_NAMELESS;
else
{
/* Scan from beginning. */
dts_temp = 0;
entry = timeline->info_list->head;
for( uint32_t i = 1; i < sample_number; i++ )
{
if( !entry )
return LSMASH_ERR_NAMELESS;
isom_sample_info_t* info = (isom_sample_info_t*)entry->data;
if( !info )
return LSMASH_ERR_NAMELESS;
dts_temp += info->duration;
entry = entry->next;
}
}
*dts = dts_temp;
}
/* Note: last_accessed_sample_number is always updated together with last_accessed_sample_dts, and vice versa. */
timeline->last_accessed_sample_dts = *dts;
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