avi: Spin out the logic to position to the next non-interleaved stream

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavformat/avidec.c

@@ -1094,6 +1094,75 @@ start_sync:
     return AVERROR_EOF;
 }
 
+static int ni_prepare_read(AVFormatContext *s)
+{
+    AVIContext *avi = s->priv_data;
+    int best_stream_index = 0;
+    AVStream *best_st     = NULL;
+    AVIStream *best_ast;
+    int64_t best_ts = INT64_MAX;
+    int i;
+
+    for (i = 0; i < s->nb_streams; i++) {
+        AVStream *st   = s->streams[i];
+        AVIStream *ast = st->priv_data;
+        int64_t ts     = ast->frame_offset;
+        int64_t last_ts;
+
+        if (!st->nb_index_entries)
+            continue;
+
+        last_ts = st->index_entries[st->nb_index_entries - 1].timestamp;
+        if (!ast->remaining && ts > last_ts)
+            continue;
+
+        ts = av_rescale_q(ts, st->time_base,
+                          (AVRational) { FFMAX(1, ast->sample_size),
+                                         AV_TIME_BASE });
+
+        av_log(s, AV_LOG_TRACE, "%"PRId64" %d/%d %"PRId64"\n", ts,
+                st->time_base.num, st->time_base.den, ast->frame_offset);
+        if (ts < best_ts) {
+            best_ts           = ts;
+            best_st           = st;
+            best_stream_index = i;
+        }
+    }
+    if (!best_st)
+        return AVERROR_EOF;
+
+    best_ast = best_st->priv_data;
+    best_ts  = av_rescale_q(best_ts,
+                            (AVRational) { FFMAX(1, best_ast->sample_size),
+                                           AV_TIME_BASE },
+                            best_st->time_base);
+    if (best_ast->remaining) {
+        i = av_index_search_timestamp(best_st,
+                                      best_ts,
+                                      AVSEEK_FLAG_ANY |
+                                      AVSEEK_FLAG_BACKWARD);
+    } else {
+        i = av_index_search_timestamp(best_st, best_ts, AVSEEK_FLAG_ANY);
+        if (i >= 0)
+            best_ast->frame_offset = best_st->index_entries[i].timestamp;
+    }
+
+    if (i >= 0) {
+        int64_t pos = best_st->index_entries[i].pos;
+        pos += best_ast->packet_size - best_ast->remaining;
+        avio_seek(s->pb, pos + 8, SEEK_SET);
+
+        assert(best_ast->remaining <= best_ast->packet_size);
+
+        avi->stream_index = best_stream_index;
+        if (!best_ast->remaining)
+            best_ast->packet_size =
+            best_ast->remaining   = best_st->index_entries[i].size;
+    }
+
+    return 0;
+}
+
 static int avi_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     AVIContext *avi = s->priv_data;
@@ -1109,68 +1178,9 @@ static int avi_read_packet(AVFormatContext *s, AVPacket *pkt)
     }
 
     if (avi->non_interleaved) {
-        int best_stream_index = 0;
-        AVStream *best_st     = NULL;
-        AVIStream *best_ast;
-        int64_t best_ts = INT64_MAX;
-        int i;
-
-        for (i = 0; i < s->nb_streams; i++) {
-            AVStream *st   = s->streams[i];
-            AVIStream *ast = st->priv_data;
-            int64_t ts     = ast->frame_offset;
-            int64_t last_ts;
-
-            if (!st->nb_index_entries)
-                continue;
-
-            last_ts = st->index_entries[st->nb_index_entries - 1].timestamp;
-            if (!ast->remaining && ts > last_ts)
-                continue;
-
-            ts = av_rescale_q(ts, st->time_base,
-                              (AVRational) { FFMAX(1, ast->sample_size),
-                                             AV_TIME_BASE });
-
-            av_log(s, AV_LOG_TRACE, "%"PRId64" %d/%d %"PRId64"\n", ts,
-                    st->time_base.num, st->time_base.den, ast->frame_offset);
-            if (ts < best_ts) {
-                best_ts           = ts;
-                best_st           = st;
-                best_stream_index = i;
-            }
-        }
-        if (!best_st)
-            return AVERROR_EOF;
-
-        best_ast = best_st->priv_data;
-        best_ts  = av_rescale_q(best_ts,
-                                (AVRational) { FFMAX(1, best_ast->sample_size),
-                                               AV_TIME_BASE },
-                                best_st->time_base);
-        if (best_ast->remaining) {
-            i = av_index_search_timestamp(best_st,
-                                          best_ts,
-                                          AVSEEK_FLAG_ANY |
-                                          AVSEEK_FLAG_BACKWARD);
-        } else {
-            i = av_index_search_timestamp(best_st, best_ts, AVSEEK_FLAG_ANY);
-            if (i >= 0)
-                best_ast->frame_offset = best_st->index_entries[i].timestamp;
-        }
-
-        if (i >= 0) {
-            int64_t pos = best_st->index_entries[i].pos;
-            pos += best_ast->packet_size - best_ast->remaining;
-            avio_seek(s->pb, pos + 8, SEEK_SET);
-
-            assert(best_ast->remaining <= best_ast->packet_size);
-
-            avi->stream_index = best_stream_index;
-            if (!best_ast->remaining)
-                best_ast->packet_size =
-                best_ast->remaining   = best_st->index_entries[i].size;
-        }
+        err = ni_prepare_read(s);
+        if (err < 0)
+            return err;
     }
 
 resync: