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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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h264parse: unobfuscate frame parsing code
This commit is contained in:
Mark Nauwelaerts
parent
c835325536
commit
1cbd755a2c
2 changed files with 102 additions and 109 deletions
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@ -177,11 +177,7 @@ gst_h264_parse_reset_frame (GstH264Parse * h264parse)
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GST_DEBUG_OBJECT (h264parse, "reset frame");
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/* done parsing; reset state */
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h264parse->nalu.valid = FALSE;
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h264parse->nalu.offset = 0;
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h264parse->nalu.sc_offset = 0;
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h264parse->nalu.size = 0;
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h264parse->current_off = 0;
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h264parse->current_off = -1;
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h264parse->picture_start = FALSE;
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h264parse->update_caps = FALSE;
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@ -656,10 +652,12 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
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GstH264Parse *h264parse = GST_H264_PARSE (parse);
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GstBuffer *buffer = frame->buffer;
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guint8 *data;
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guint size, current_off = 0;
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gboolean drain;
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guint size;
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gint current_off = 0;
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gboolean drain, nonext;
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GstH264NalParser *nalparser = h264parse->nalparser;
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GstH264NalUnit nalu;
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GstH264ParserResult pres;
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/* expect at least 3 bytes startcode == sc, and 2 bytes NALU payload */
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if (G_UNLIKELY (GST_BUFFER_SIZE (buffer) < 5))
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@ -681,16 +679,38 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
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data = GST_BUFFER_DATA (buffer);
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size = GST_BUFFER_SIZE (buffer);
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drain = FALSE;
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nalu = h264parse->nalu;
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drain = GST_BASE_PARSE_DRAINING (parse);
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nonext = FALSE;
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current_off = h264parse->current_off;
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if (current_off < 0)
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current_off = 0;
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g_assert (current_off < size);
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GST_DEBUG_OBJECT (h264parse, "last parse position %d", current_off);
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/* check for initial skip */
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if (h264parse->current_off == -1) {
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pres =
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gst_h264_parser_identify_nalu_unchecked (nalparser, data, current_off,
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size, &nalu);
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switch (pres) {
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case GST_H264_PARSER_OK:
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if (nalu.sc_offset > 0) {
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*skipsize = nalu.sc_offset;
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goto skip;
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}
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break;
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case GST_H264_PARSER_NO_NAL:
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*skipsize = size - 3;
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goto skip;
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break;
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default:
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g_assert_not_reached ();
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break;
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}
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}
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GST_DEBUG_OBJECT (h264parse, "last parse position %u", current_off);
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while (TRUE) {
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GstH264ParserResult pres;
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if (h264parse->packetized_chunked)
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pres =
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gst_h264_parser_identify_nalu_unchecked (nalparser, data, current_off,
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@ -702,99 +722,85 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
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switch (pres) {
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case GST_H264_PARSER_OK:
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GST_DEBUG_OBJECT (h264parse, "complete nal found. "
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"current offset: %u, Nal offset: %u, Nal Size: %u",
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current_off, nalu.offset, nalu.size);
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GST_DEBUG_OBJECT (h264parse, "current off. %u",
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nalu.offset + nalu.size);
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if (!h264parse->nalu.size && !h264parse->nalu.valid)
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h264parse->nalu = nalu;
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/* need 2 bytes of next nal */
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if (!h264parse->packetized_chunked &&
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(nalu.offset + nalu.size + 4 + 2 > size)) {
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if (GST_BASE_PARSE_DRAINING (parse)) {
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drain = TRUE;
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} else {
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GST_DEBUG_OBJECT (h264parse, "need more bytes of next nal");
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current_off = nalu.sc_offset;
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goto more;
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}
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} else if (h264parse->packetized_chunked) {
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/* normal next nal based collection not possible,
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* _chain will have to tell us whether this was last one for AU */
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drain = h264parse->packetized_last;
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}
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GST_DEBUG_OBJECT (h264parse, "complete nal (offset, size): (%u, %u) ",
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nalu.offset, nalu.size);
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break;
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case GST_H264_PARSER_BROKEN_LINK:
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return FALSE;
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case GST_H264_PARSER_ERROR:
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current_off = size - 3;
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goto parsing_error;
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case GST_H264_PARSER_NO_NAL:
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/* don't expect to have found any NAL so far */
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g_assert (h264parse->nalu.size == 0);
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current_off = h264parse->nalu.sc_offset = size - 3;
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goto more;
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case GST_H264_PARSER_BROKEN_DATA:
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GST_WARNING_OBJECT (h264parse, "input stream is corrupt; "
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"it contains a NAL unit of length %d", nalu.size);
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/* broken nal at start -> arrange to skip it,
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* otherwise have it terminate current au
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* (and so it will be skipped on next frame round) */
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if (nalu.sc_offset == h264parse->nalu.sc_offset) {
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*skipsize = nalu.offset;
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GST_DEBUG_OBJECT (h264parse, "skipping broken nal");
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goto invalid;
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} else {
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nalu.size = 0;
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goto end;
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}
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case GST_H264_PARSER_NO_NAL_END:
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GST_DEBUG_OBJECT (h264parse, "not a complete nal found at offset %u",
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nalu.offset);
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current_off = nalu.sc_offset;
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/* We keep the reference to this nal so we start over the parsing
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* here */
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if (!h264parse->nalu.size && !h264parse->nalu.valid)
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h264parse->nalu = nalu;
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if (GST_BASE_PARSE_DRAINING (parse)) {
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drain = TRUE;
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GST_DEBUG_OBJECT (h264parse, "draining NAL %u %u %u", size,
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h264parse->nalu.offset, h264parse->nalu.size);
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/* Can't parse the nalu */
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if (size - h264parse->nalu.offset < 2) {
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*skipsize = nalu.offset;
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goto invalid;
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}
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/* We parse it anyway */
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/* if draining, accept it as complete nal */
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if (drain) {
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nonext = TRUE;
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nalu.size = size - nalu.offset;
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GST_DEBUG_OBJECT (h264parse, "draining, accepting with size %u",
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nalu.size);
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/* if it's not too short at least */
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if (nalu.size < 2)
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goto broken;
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break;
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}
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/* otherwise need more */
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goto more;
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case GST_H264_PARSER_BROKEN_LINK:
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g_assert_not_reached ();
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break;
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case GST_H264_PARSER_ERROR:
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/* should not really occur either */
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GST_DEBUG_OBJECT (h264parse, "error parsing Nal Unit");
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/* fall-through */
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case GST_H264_PARSER_NO_NAL:
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g_assert_not_reached ();
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break;
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case GST_H264_PARSER_BROKEN_DATA:
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GST_WARNING_OBJECT (h264parse, "input stream is corrupt; "
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"it contains a NAL unit of length %u", nalu.size);
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broken:
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/* broken nal at start -> arrange to skip it,
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* otherwise have it terminate current au
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* (and so it will be skipped on next frame round) */
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if (current_off == 0) {
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GST_DEBUG_OBJECT (h264parse, "skipping broken nal");
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*skipsize = nalu.offset;
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goto skip;
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} else {
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GST_DEBUG_OBJECT (h264parse, "terminating au");
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nalu.size = 0;
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nalu.offset = nalu.sc_offset;
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goto end;
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}
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break;
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default:
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g_assert_not_reached ();
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break;
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}
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current_off = nalu.offset + nalu.size;
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GST_DEBUG_OBJECT (h264parse, "%p complete nal found. Off: %u, Size: %u",
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data, nalu.offset, nalu.size);
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/* simulate no next nal if none needed */
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nonext = nonext || (h264parse->align == GST_H264_PARSE_ALIGN_NAL);
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if (!nonext && !h264parse->packetized_chunked) {
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if (nalu.offset + nalu.size + 4 + 2 > size) {
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GST_DEBUG_OBJECT (h264parse, "not enough data for next NALU");
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if (drain) {
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GST_DEBUG_OBJECT (h264parse, "but draining anyway");
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nonext = TRUE;
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} else {
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goto more;
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}
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}
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}
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gst_h264_parse_process_nal (h264parse, &nalu);
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/* simulate no next nal if none needed */
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drain = drain || (h264parse->align == GST_H264_PARSE_ALIGN_NAL);
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if (nonext)
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break;
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/* In packetized mode we know there's only on NALU in each input packet,
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* but we may not have seen the whole AU already, possibly need more */
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if (h264parse->packetized_chunked) {
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if (drain)
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if (h264parse->packetized_last)
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break;
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/* next NALU expected at end of current data */
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current_off = size;
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@ -802,42 +808,30 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
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}
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/* if no next nal, we know it's complete here */
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if (drain || gst_h264_parse_collect_nal (h264parse, data, size, &nalu))
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if (gst_h264_parse_collect_nal (h264parse, data, size, &nalu))
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break;
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GST_DEBUG_OBJECT (h264parse, "Looking for more");
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current_off = nalu.offset + nalu.size;
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}
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end:
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*skipsize = h264parse->nalu.sc_offset;
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*framesize = nalu.offset + nalu.size - h264parse->nalu.sc_offset;
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h264parse->current_off = current_off;
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*framesize = nalu.offset + nalu.size;
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return TRUE;
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parsing_error:
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GST_DEBUG_OBJECT (h264parse, "error parsing Nal Unit");
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more:
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/* ask for best next available */
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*framesize = G_MAXUINT;
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if (!h264parse->nalu.size) {
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/* skip up to initial startcode */
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*skipsize = h264parse->nalu.sc_offset;
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/* but mind some stuff will have been skipped */
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g_assert (current_off >= *skipsize);
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current_off -= *skipsize;
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h264parse->nalu.sc_offset = 0;
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} else {
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*skipsize = 0;
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}
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*skipsize = 0;
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/* Restart parsing from here next time */
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h264parse->current_off = current_off;
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if (current_off > 0)
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h264parse->current_off = current_off;
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return FALSE;
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invalid:
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skip:
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GST_DEBUG_OBJECT (h264parse, "skipping %d", *skipsize);
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gst_h264_parse_reset_frame (h264parse);
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return FALSE;
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}
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@ -67,10 +67,9 @@ struct _GstH264Parse
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/* state */
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GstH264NalParser *nalparser;
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GstH264NalUnit nalu;
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guint align;
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guint format;
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guint current_off;
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gint current_off;
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gboolean packetized_last;
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gboolean packetized_chunked;
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