From 1cbd755a2cd45531076c7b19ef194b77d5575cb0 Mon Sep 17 00:00:00 2001 From: Mark Nauwelaerts Date: Fri, 10 Feb 2012 14:46:00 +0100 Subject: [PATCH] h264parse: unobfuscate frame parsing code --- gst/videoparsers/gsth264parse.c | 208 ++++++++++++++++---------------- gst/videoparsers/gsth264parse.h | 3 +- 2 files changed, 102 insertions(+), 109 deletions(-) diff --git a/gst/videoparsers/gsth264parse.c b/gst/videoparsers/gsth264parse.c index 3482d5bfe4..545a08dbae 100644 --- a/gst/videoparsers/gsth264parse.c +++ b/gst/videoparsers/gsth264parse.c @@ -177,11 +177,7 @@ gst_h264_parse_reset_frame (GstH264Parse * h264parse) GST_DEBUG_OBJECT (h264parse, "reset frame"); /* done parsing; reset state */ - h264parse->nalu.valid = FALSE; - h264parse->nalu.offset = 0; - h264parse->nalu.sc_offset = 0; - h264parse->nalu.size = 0; - h264parse->current_off = 0; + h264parse->current_off = -1; h264parse->picture_start = FALSE; h264parse->update_caps = FALSE; @@ -656,10 +652,12 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse, GstH264Parse *h264parse = GST_H264_PARSE (parse); GstBuffer *buffer = frame->buffer; guint8 *data; - guint size, current_off = 0; - gboolean drain; + guint size; + gint current_off = 0; + gboolean drain, nonext; GstH264NalParser *nalparser = h264parse->nalparser; GstH264NalUnit nalu; + GstH264ParserResult pres; /* expect at least 3 bytes startcode == sc, and 2 bytes NALU payload */ if (G_UNLIKELY (GST_BUFFER_SIZE (buffer) < 5)) @@ -681,16 +679,38 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse, data = GST_BUFFER_DATA (buffer); size = GST_BUFFER_SIZE (buffer); - drain = FALSE; - nalu = h264parse->nalu; + drain = GST_BASE_PARSE_DRAINING (parse); + nonext = FALSE; + current_off = h264parse->current_off; - + if (current_off < 0) + current_off = 0; g_assert (current_off < size); + GST_DEBUG_OBJECT (h264parse, "last parse position %d", current_off); + + /* check for initial skip */ + if (h264parse->current_off == -1) { + pres = + gst_h264_parser_identify_nalu_unchecked (nalparser, data, current_off, + size, &nalu); + switch (pres) { + case GST_H264_PARSER_OK: + if (nalu.sc_offset > 0) { + *skipsize = nalu.sc_offset; + goto skip; + } + break; + case GST_H264_PARSER_NO_NAL: + *skipsize = size - 3; + goto skip; + break; + default: + g_assert_not_reached (); + break; + } + } - GST_DEBUG_OBJECT (h264parse, "last parse position %u", current_off); while (TRUE) { - GstH264ParserResult pres; - if (h264parse->packetized_chunked) pres = gst_h264_parser_identify_nalu_unchecked (nalparser, data, current_off, @@ -702,99 +722,85 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse, switch (pres) { case GST_H264_PARSER_OK: - GST_DEBUG_OBJECT (h264parse, "complete nal found. " - "current offset: %u, Nal offset: %u, Nal Size: %u", - current_off, nalu.offset, nalu.size); - - GST_DEBUG_OBJECT (h264parse, "current off. %u", - nalu.offset + nalu.size); - - if (!h264parse->nalu.size && !h264parse->nalu.valid) - h264parse->nalu = nalu; - - /* need 2 bytes of next nal */ - if (!h264parse->packetized_chunked && - (nalu.offset + nalu.size + 4 + 2 > size)) { - if (GST_BASE_PARSE_DRAINING (parse)) { - drain = TRUE; - } else { - GST_DEBUG_OBJECT (h264parse, "need more bytes of next nal"); - current_off = nalu.sc_offset; - goto more; - } - } else if (h264parse->packetized_chunked) { - /* normal next nal based collection not possible, - * _chain will have to tell us whether this was last one for AU */ - drain = h264parse->packetized_last; - } + GST_DEBUG_OBJECT (h264parse, "complete nal (offset, size): (%u, %u) ", + nalu.offset, nalu.size); break; - case GST_H264_PARSER_BROKEN_LINK: - return FALSE; - case GST_H264_PARSER_ERROR: - current_off = size - 3; - goto parsing_error; - case GST_H264_PARSER_NO_NAL: - /* don't expect to have found any NAL so far */ - g_assert (h264parse->nalu.size == 0); - current_off = h264parse->nalu.sc_offset = size - 3; - goto more; - case GST_H264_PARSER_BROKEN_DATA: - GST_WARNING_OBJECT (h264parse, "input stream is corrupt; " - "it contains a NAL unit of length %d", nalu.size); - - /* broken nal at start -> arrange to skip it, - * otherwise have it terminate current au - * (and so it will be skipped on next frame round) */ - if (nalu.sc_offset == h264parse->nalu.sc_offset) { - *skipsize = nalu.offset; - - GST_DEBUG_OBJECT (h264parse, "skipping broken nal"); - goto invalid; - } else { - nalu.size = 0; - goto end; - } case GST_H264_PARSER_NO_NAL_END: GST_DEBUG_OBJECT (h264parse, "not a complete nal found at offset %u", nalu.offset); - - current_off = nalu.sc_offset; - /* We keep the reference to this nal so we start over the parsing - * here */ - if (!h264parse->nalu.size && !h264parse->nalu.valid) - h264parse->nalu = nalu; - - if (GST_BASE_PARSE_DRAINING (parse)) { - drain = TRUE; - GST_DEBUG_OBJECT (h264parse, "draining NAL %u %u %u", size, - h264parse->nalu.offset, h264parse->nalu.size); - /* Can't parse the nalu */ - if (size - h264parse->nalu.offset < 2) { - *skipsize = nalu.offset; - goto invalid; - } - - /* We parse it anyway */ + /* if draining, accept it as complete nal */ + if (drain) { + nonext = TRUE; nalu.size = size - nalu.offset; + GST_DEBUG_OBJECT (h264parse, "draining, accepting with size %u", + nalu.size); + /* if it's not too short at least */ + if (nalu.size < 2) + goto broken; break; } + /* otherwise need more */ goto more; + case GST_H264_PARSER_BROKEN_LINK: + g_assert_not_reached (); + break; + case GST_H264_PARSER_ERROR: + /* should not really occur either */ + GST_DEBUG_OBJECT (h264parse, "error parsing Nal Unit"); + /* fall-through */ + case GST_H264_PARSER_NO_NAL: + g_assert_not_reached (); + break; + case GST_H264_PARSER_BROKEN_DATA: + GST_WARNING_OBJECT (h264parse, "input stream is corrupt; " + "it contains a NAL unit of length %u", nalu.size); + broken: + /* broken nal at start -> arrange to skip it, + * otherwise have it terminate current au + * (and so it will be skipped on next frame round) */ + if (current_off == 0) { + GST_DEBUG_OBJECT (h264parse, "skipping broken nal"); + *skipsize = nalu.offset; + goto skip; + } else { + GST_DEBUG_OBJECT (h264parse, "terminating au"); + nalu.size = 0; + nalu.offset = nalu.sc_offset; + goto end; + } + break; + default: + g_assert_not_reached (); + break; } - current_off = nalu.offset + nalu.size; - GST_DEBUG_OBJECT (h264parse, "%p complete nal found. Off: %u, Size: %u", data, nalu.offset, nalu.size); + /* simulate no next nal if none needed */ + nonext = nonext || (h264parse->align == GST_H264_PARSE_ALIGN_NAL); + + if (!nonext && !h264parse->packetized_chunked) { + if (nalu.offset + nalu.size + 4 + 2 > size) { + GST_DEBUG_OBJECT (h264parse, "not enough data for next NALU"); + if (drain) { + GST_DEBUG_OBJECT (h264parse, "but draining anyway"); + nonext = TRUE; + } else { + goto more; + } + } + } + gst_h264_parse_process_nal (h264parse, &nalu); - /* simulate no next nal if none needed */ - drain = drain || (h264parse->align == GST_H264_PARSE_ALIGN_NAL); + if (nonext) + break; /* In packetized mode we know there's only on NALU in each input packet, * but we may not have seen the whole AU already, possibly need more */ if (h264parse->packetized_chunked) { - if (drain) + if (h264parse->packetized_last) break; /* next NALU expected at end of current data */ current_off = size; @@ -802,42 +808,30 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse, } /* if no next nal, we know it's complete here */ - if (drain || gst_h264_parse_collect_nal (h264parse, data, size, &nalu)) + if (gst_h264_parse_collect_nal (h264parse, data, size, &nalu)) break; GST_DEBUG_OBJECT (h264parse, "Looking for more"); + current_off = nalu.offset + nalu.size; } end: - *skipsize = h264parse->nalu.sc_offset; - *framesize = nalu.offset + nalu.size - h264parse->nalu.sc_offset; - h264parse->current_off = current_off; - + *framesize = nalu.offset + nalu.size; return TRUE; -parsing_error: - GST_DEBUG_OBJECT (h264parse, "error parsing Nal Unit"); - more: /* ask for best next available */ *framesize = G_MAXUINT; - if (!h264parse->nalu.size) { - /* skip up to initial startcode */ - *skipsize = h264parse->nalu.sc_offset; - /* but mind some stuff will have been skipped */ - g_assert (current_off >= *skipsize); - current_off -= *skipsize; - h264parse->nalu.sc_offset = 0; - } else { - *skipsize = 0; - } + *skipsize = 0; /* Restart parsing from here next time */ - h264parse->current_off = current_off; + if (current_off > 0) + h264parse->current_off = current_off; return FALSE; -invalid: +skip: + GST_DEBUG_OBJECT (h264parse, "skipping %d", *skipsize); gst_h264_parse_reset_frame (h264parse); return FALSE; } diff --git a/gst/videoparsers/gsth264parse.h b/gst/videoparsers/gsth264parse.h index ff6eb59f01..61afe93878 100644 --- a/gst/videoparsers/gsth264parse.h +++ b/gst/videoparsers/gsth264parse.h @@ -67,10 +67,9 @@ struct _GstH264Parse /* state */ GstH264NalParser *nalparser; - GstH264NalUnit nalu; guint align; guint format; - guint current_off; + gint current_off; gboolean packetized_last; gboolean packetized_chunked;