mirror of https://git.ffmpeg.org/ffmpeg.git
h264: Refactor decode_nal_units
This commit is contained in:
Luca Barbato
Janne Grunau
parent
c389a80494
commit
e10fd08aa7
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@ -1281,6 +1281,116 @@ int ff_set_ref_count(H264Context *h)
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return 0;
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}
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static int find_start_code(const uint8_t *buf, int buf_size,
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int buf_index, int next_avc)
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{
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// start code prefix search
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for (; buf_index + 3 < next_avc; buf_index++)
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// This should always succeed in the first iteration.
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if (buf[buf_index] == 0 &&
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buf[buf_index + 1] == 0 &&
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buf[buf_index + 2] == 1)
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break;
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if (buf_index + 3 >= buf_size)
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return buf_size;
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return buf_index + 3;
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}
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static int get_avc_nalsize(H264Context *h, const uint8_t *buf,
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int buf_size, int *buf_index)
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{
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int i, nalsize = 0;
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if (*buf_index >= buf_size - h->nal_length_size)
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return -1;
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for (i = 0; i < h->nal_length_size; i++)
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nalsize = (nalsize << 8) | buf[(*buf_index)++];
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if (nalsize <= 0 || nalsize > buf_size - *buf_index) {
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av_log(h->avctx, AV_LOG_ERROR,
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"AVC: nal size %d\n", nalsize);
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return -1;
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}
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return nalsize;
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}
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static int get_bit_length(H264Context *h, const uint8_t *buf,
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const uint8_t *ptr, int dst_length,
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int i, int next_avc)
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{
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if ((h->workaround_bugs & FF_BUG_AUTODETECT) && i + 3 < next_avc &&
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buf[i] == 0x00 && buf[i + 1] == 0x00 &&
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buf[i + 2] == 0x01 && buf[i + 3] == 0xE0)
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h->workaround_bugs |= FF_BUG_TRUNCATED;
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if (!(h->workaround_bugs & FF_BUG_TRUNCATED))
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while (dst_length > 0 && ptr[dst_length - 1] == 0)
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dst_length--;
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if (!dst_length)
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return 0;
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return 8 * dst_length - decode_rbsp_trailing(h, ptr + dst_length - 1);
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}
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static int get_last_needed_nal(H264Context *h, const uint8_t *buf, int buf_size)
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{
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int next_avc = h->is_avc ? 0 : buf_size;
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int nal_index = 0;
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int buf_index = 0;
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int nals_needed = 0;
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while(1) {
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int nalsize = 0;
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int dst_length, bit_length, consumed;
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const uint8_t *ptr;
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if (buf_index >= next_avc) {
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nalsize = get_avc_nalsize(h, buf, buf_size, &buf_index);
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if (nalsize < 0)
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break;
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next_avc = buf_index + nalsize;
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} else {
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buf_index = find_start_code(buf, buf_size, buf_index, next_avc);
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if (buf_index >= buf_size)
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break;
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}
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ptr = ff_h264_decode_nal(h, buf + buf_index, &dst_length, &consumed,
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next_avc - buf_index);
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if (ptr == NULL || dst_length < 0)
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return AVERROR_INVALIDDATA;
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buf_index += consumed;
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bit_length = get_bit_length(h, buf, ptr, dst_length,
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buf_index, next_avc);
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nal_index++;
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/* packets can sometimes contain multiple PPS/SPS,
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* e.g. two PAFF field pictures in one packet, or a demuxer
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* which splits NALs strangely if so, when frame threading we
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* can't start the next thread until we've read all of them */
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switch (h->nal_unit_type) {
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case NAL_SPS:
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case NAL_PPS:
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nals_needed = nal_index;
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break;
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case NAL_DPA:
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case NAL_IDR_SLICE:
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case NAL_SLICE:
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init_get_bits(&h->gb, ptr, bit_length);
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if (!get_ue_golomb(&h->gb))
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nals_needed = nal_index;
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}
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}
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return nals_needed;
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}
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static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
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int parse_extradata)
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{
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@ -1289,7 +1399,6 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
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int buf_index;
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unsigned context_count;
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int next_avc;
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int pass = !(avctx->active_thread_type & FF_THREAD_FRAME);
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int nals_needed = 0; ///< number of NALs that need decoding before the next frame thread starts
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int nal_index;
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int ret = 0;
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@ -1302,7 +1411,10 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
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ff_h264_reset_sei(h);
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}
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for (; pass <= 1; pass++) {
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if (avctx->active_thread_type & FF_THREAD_FRAME)
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nals_needed = get_last_needed_nal(h, buf, buf_size);
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{
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buf_index = 0;
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context_count = 0;
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next_avc = h->is_avc ? 0 : buf_size;
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@ -1312,38 +1424,18 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
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int dst_length;
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int bit_length;
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const uint8_t *ptr;
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int i, nalsize = 0;
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int nalsize = 0;
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int err;
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if (buf_index >= next_avc) {
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if (buf_index >= buf_size - h->nal_length_size)
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nalsize = get_avc_nalsize(h, buf, buf_size, &buf_index);
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if (nalsize < 0)
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break;
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nalsize = 0;
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for (i = 0; i < h->nal_length_size; i++)
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nalsize = (nalsize << 8) | buf[buf_index++];
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if (nalsize <= 0 || nalsize > buf_size - buf_index) {
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av_log(h->avctx, AV_LOG_ERROR,
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"AVC: nal size %d\n", nalsize);
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break;
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}
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next_avc = buf_index + nalsize;
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} else {
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// start code prefix search
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for (; buf_index + 3 < next_avc; buf_index++)
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// This should always succeed in the first iteration.
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if (buf[buf_index] == 0 &&
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buf[buf_index + 1] == 0 &&
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buf[buf_index + 2] == 1)
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break;
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if (buf_index + 3 >= buf_size) {
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buf_index = buf_size;
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buf_index = find_start_code(buf, buf_size, buf_index, next_avc);
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if (buf_index >= buf_size)
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break;
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}
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buf_index += 3;
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if (buf_index >= next_avc)
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continue;
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}
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hx = h->thread_context[context_count];
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@ -1354,18 +1446,9 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
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ret = -1;
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goto end;
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}
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i = buf_index + consumed;
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if ((h->workaround_bugs & FF_BUG_AUTODETECT) && i + 3 < next_avc &&
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buf[i] == 0x00 && buf[i + 1] == 0x00 &&
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buf[i + 2] == 0x01 && buf[i + 3] == 0xE0)
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h->workaround_bugs |= FF_BUG_TRUNCATED;
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if (!(h->workaround_bugs & FF_BUG_TRUNCATED))
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while (dst_length > 0 && ptr[dst_length - 1] == 0)
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dst_length--;
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bit_length = !dst_length ? 0
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: (8 * dst_length -
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decode_rbsp_trailing(h, ptr + dst_length - 1));
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bit_length = get_bit_length(h, buf, ptr, dst_length,
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buf_index + consumed, next_avc);
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if (h->avctx->debug & FF_DEBUG_STARTCODE)
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av_log(h->avctx, AV_LOG_DEBUG,
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@ -1380,26 +1463,6 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
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buf_index += consumed;
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nal_index++;
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if (pass == 0) {
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/* packets can sometimes contain multiple PPS/SPS,
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* e.g. two PAFF field pictures in one packet, or a demuxer
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* which splits NALs strangely if so, when frame threading we
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* can't start the next thread until we've read all of them */
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switch (hx->nal_unit_type) {
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case NAL_SPS:
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case NAL_PPS:
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nals_needed = nal_index;
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break;
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case NAL_DPA:
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case NAL_IDR_SLICE:
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case NAL_SLICE:
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init_get_bits(&hx->gb, ptr, bit_length);
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if (!get_ue_golomb(&hx->gb))
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nals_needed = nal_index;
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}
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continue;
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}
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if (avctx->skip_frame >= AVDISCARD_NONREF &&
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h->nal_ref_idc == 0 &&
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h->nal_unit_type != NAL_SEI)
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