static int decode_styl(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
int i;
int style_entries = AV_RB16(tsmb);
tsmb += 2;
// A single style record is of length 12 bytes.
if (m->tracksize + m->size_var + 2 + style_entries * 12 > avpkt->size)
return -1;
m->style_entries = style_entries;
m->box_flags |= STYL_BOX;
for(i = 0; i < m->style_entries; i++) {
m->s_temp = av_malloc(sizeof(*m->s_temp));
if (!m->s_temp) {
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
m->s_temp->style_start = AV_RB16(tsmb);
tsmb += 2;
m->s_temp->style_end = AV_RB16(tsmb);
if ( m->s_temp->style_end < m->s_temp->style_start
|| (m->count_s && m->s_temp->style_start < m->s[m->count_s - 1]->style_end)) {
av_freep(&m->s_temp);
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
tsmb += 2;
m->s_temp->style_fontID = AV_RB16(tsmb);
tsmb += 2;
m->s_temp->style_flag = AV_RB8(tsmb);
tsmb++;
m->s_temp->fontsize = AV_RB8(tsmb);
av_dynarray_add(&m->s, &m->count_s, m->s_temp);
if(!m->s) {
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
tsmb++;
// text-color-rgba
tsmb += 4;
}
return 0;
}
static int mov_text_decode_frame(AVCodecContext *avctx,
void *data, int *got_sub_ptr, AVPacket *avpkt)
{
AVSubtitle *sub = data;
MovTextContext *m = avctx->priv_data;
int ret, ts_start, ts_end;
AVBPrint buf;
char *ptr = avpkt->data;
char *end;
int text_length, tsmb_type, ret_tsmb;
uint64_t tsmb_size;
const uint8_t *tsmb;
if (!ptr || avpkt->size < 2)
return AVERROR_INVALIDDATA;
/*
* A packet of size two with value zero is an empty subtitle
* used to mark the end of the previous non-empty subtitle.
* We can just drop them here as we have duration information
* already. If the value is non-zero, then it's technically a
* bad packet.
*/
if (avpkt->size == 2)
return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;
/*
* The first two bytes of the packet are the length of the text string
* In complex cases, there are style descriptors appended to the string
* so we can't just assume the packet size is the string size.
*/
text_length = AV_RB16(ptr);
end = ptr + FFMIN(2 + text_length, avpkt->size);
ptr += 2;
ts_start = av_rescale_q(avpkt->pts,
avctx->time_base,
(AVRational){1,100});
ts_end = av_rescale_q(avpkt->pts + avpkt->duration,
avctx->time_base,
(AVRational){1,100});
tsmb_size = 0;
m->tracksize = 2 + text_length;
m->style_entries = 0;
m->box_flags = 0;
m->count_s = 0;
// Note that the spec recommends lines be no longer than 2048 characters.
av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
if (text_length + 2 != avpkt->size) {
while (m->tracksize + 8 <= avpkt->size) {
// A box is a minimum of 8 bytes.
tsmb = ptr + m->tracksize - 2;
tsmb_size = AV_RB32(tsmb);
tsmb += 4;
tsmb_type = AV_RB32(tsmb);
tsmb += 4;
if (tsmb_size == 1) {
if (m->tracksize + 16 > avpkt->size)
break;
tsmb_size = AV_RB64(tsmb);
tsmb += 8;
m->size_var = 16;
} else
m->size_var = 8;
//size_var is equal to 8 or 16 depending on the size of box
if (m->tracksize + tsmb_size > avpkt->size)
break;
for (size_t i = 0; i < box_count; i++) {
if (tsmb_type == box_types[i].type) {
if (m->tracksize + m->size_var + box_types[i].base_size > avpkt->size)
break;
ret_tsmb = box_types[i].decode(tsmb, m, avpkt);
if (ret_tsmb == -1)
break;
}
}
m->tracksize = m->tracksize + tsmb_size;
}
text_to_ass(&buf, ptr, end, m);
mov_text_cleanup(m);
} else
text_to_ass(&buf, ptr, end, m);
ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_end - ts_start);
av_bprint_finalize(&buf, NULL);
if (ret < 0)
return ret;
*got_sub_ptr = sub->num_rects > 0;
return avpkt->size;
}