lavf: deobfuscate read_frame_internal().

Split off packet parsing into a separate function. Parse full packets at
once and store them in a queue, eliminating the need for tracking
parsing state in AVStream.

The horrible unreadable loop in read_frame_internal() now isn't weirdly
ordered and doesn't contain evil gotos, so it should be much easier to
understand.

compute_pkt_fields() now invents slightly different timestamps for two
raw vc1 tests, due to has_b_frames being set a bit later. They shouldn't
be more wrong (or right) than previous ones.

1 files changed, 4 insertions, 13 deletions

diff --git a/libavformat/seek.c b/libavformat/seek.c
index e64021dc78..524cd87e6a 100644
--- a/libavformat/seek.c
+++ b/libavformat/seek.c
@@ -409,13 +409,13 @@ AVParserState *ff_store_parser_state(AVFormatContext *s)
     state->fpos = avio_tell(s->pb);
 
     // copy context structures
-    state->cur_st                           = s->cur_st;
     state->packet_buffer                    = s->packet_buffer;
+    state->parse_queue                      = s->parse_queue;
     state->raw_packet_buffer                = s->raw_packet_buffer;
     state->raw_packet_buffer_remaining_size = s->raw_packet_buffer_remaining_size;
 
-    s->cur_st                               = NULL;
     s->packet_buffer                        = NULL;
+    s->parse_queue                          = NULL;
     s->raw_packet_buffer                    = NULL;
     s->raw_packet_buffer_remaining_size     = RAW_PACKET_BUFFER_SIZE;
 
@@ -429,19 +429,13 @@ AVParserState *ff_store_parser_state(AVFormatContext *s)
         ss->last_IP_pts   = st->last_IP_pts;
         ss->cur_dts       = st->cur_dts;
         ss->reference_dts = st->reference_dts;
-        ss->cur_ptr       = st->cur_ptr;
-        ss->cur_len       = st->cur_len;
         ss->probe_packets = st->probe_packets;
-        ss->cur_pkt       = st->cur_pkt;
 
         st->parser        = NULL;
         st->last_IP_pts   = AV_NOPTS_VALUE;
         st->cur_dts       = AV_NOPTS_VALUE;
         st->reference_dts = AV_NOPTS_VALUE;
-        st->cur_ptr       = NULL;
-        st->cur_len       = 0;
         st->probe_packets = MAX_PROBE_PACKETS;
-        av_init_packet(&st->cur_pkt);
     }
 
     return state;
@@ -460,8 +454,8 @@ void ff_restore_parser_state(AVFormatContext *s, AVParserState *state)
     avio_seek(s->pb, state->fpos, SEEK_SET);
 
     // copy context structures
-    s->cur_st                           = state->cur_st;
     s->packet_buffer                    = state->packet_buffer;
+    s->parse_queue                      = state->parse_queue;
     s->raw_packet_buffer                = state->raw_packet_buffer;
     s->raw_packet_buffer_remaining_size = state->raw_packet_buffer_remaining_size;
 
@@ -474,10 +468,7 @@ void ff_restore_parser_state(AVFormatContext *s, AVParserState *state)
         st->last_IP_pts   = ss->last_IP_pts;
         st->cur_dts       = ss->cur_dts;
         st->reference_dts = ss->reference_dts;
-        st->cur_ptr       = ss->cur_ptr;
-        st->cur_len       = ss->cur_len;
         st->probe_packets = ss->probe_packets;
-        st->cur_pkt       = ss->cur_pkt;
     }
 
     av_free(state->stream_states);
@@ -507,10 +498,10 @@ void ff_free_parser_state(AVFormatContext *s, AVParserState *state)
         ss = &state->stream_states[i];
         if (ss->parser)
             av_parser_close(ss->parser);
-        av_free_packet(&ss->cur_pkt);
     }
 
     free_packet_list(state->packet_buffer);
+    free_packet_list(state->parse_queue);
     free_packet_list(state->raw_packet_buffer);
 
     av_free(state->stream_states);