From eef885cf861a6ac4f7410d92bbf72ddd47fac4e1 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Tim-Philipp=20M=C3=BCller?= Date: Sat, 23 Jan 2010 15:25:42 +0000 Subject: [PATCH] typefinding: optimise AC-3 typefinder a bit Make AC-3 typefinder use the DataScanCtx stuff so we don't have to do gst_type_find_peek() in the inner loop all the time. Also return when we've suggested AC3 caps, instead of continuing with the loop. --- gst/typefind/gsttypefindfunctions.c | 40 ++++++++++++++++++++----------------- 1 file changed, 22 insertions(+), 18 deletions(-) diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c index 13d807b..f8b88ed 100644 --- a/gst/typefind/gsttypefindfunctions.c +++ b/gst/typefind/gsttypefindfunctions.c @@ -1090,7 +1090,7 @@ musepack_type_find (GstTypeFind * tf, gpointer unused) } /*** audio/x-ac3 ***/ -/* This should be audio/ac3, but isn't for backwards compatibility */ +/* FIXME 0.11: should be audio/ac3, but isn't for backwards compatibility */ static GstStaticCaps ac3_caps = GST_STATIC_CAPS ("audio/x-ac3"); #define AC3_CAPS (gst_static_caps_get(&ac3_caps)) @@ -1142,47 +1142,51 @@ static const struct ac3_frmsize ac3_frmsizecod_tbl[] = { {640, {1280, 1394, 1920}} }; - static void ac3_type_find (GstTypeFind * tf, gpointer unused) { - guint8 *data = gst_type_find_peek (tf, 0, 5); - gint offset = 0; + DataScanCtx c = { 0, NULL, 0 }; /* Search for an ac3 frame; not neccesarily right at the start, but give it * a lower probability if not found right at the start. Check that the * frame is followed by a second frame at the expected offset. * We could also check the two ac3 CRCs, but we don't do that right now */ - while (data && offset < 1024) { - if (data[0] == 0x0b && data[1] == 0x77) { - guint fscod = (data[4] >> 6) & 0x03; - guint frmsizecod = data[4] & 0x3f; + while (c.offset < 1024) { + if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 5))) + break; + + if (c.data[0] == 0x0b && c.data[1] == 0x77) { + guint fscod = (c.data[4] >> 6) & 0x03; + guint frmsizecod = c.data[4] & 0x3f; if (fscod < 3 && frmsizecod < 38) { - guint frame_size = ac3_frmsizecod_tbl[frmsizecod].frm_size[fscod]; + DataScanCtx c_next = c; + guint frame_size; - data = gst_type_find_peek (tf, offset + frame_size * 2, 5); + frame_size = ac3_frmsizecod_tbl[frmsizecod].frm_size[fscod]; + if (data_scan_ctx_ensure_data (tf, &c_next, (frame_size * 2) + 5)) { + data_scan_ctx_advance (tf, &c, frame_size * 2); - if (data) { - if (data[0] == 0x0b && data[1] == 0x77) { - guint fscod2 = (data[4] >> 6) & 0x03; - guint frmsizecod2 = data[4] & 0x3f; + if (c_next.data[0] == 0x0b && c_next.data[1] == 0x77) { + guint fscod2 = (c_next.data[4] >> 6) & 0x03; + guint frmsizecod2 = c_next.data[4] & 0x3f; if (fscod == fscod2 && frmsizecod == frmsizecod2) { - int prob; + GstTypeFindProbability prob; - if (offset == 0) + if (c.offset == 0) prob = GST_TYPE_FIND_MAXIMUM; else prob = GST_TYPE_FIND_NEARLY_CERTAIN; + gst_type_find_suggest (tf, prob, AC3_CAPS); + return; } } } } } - offset++; - data = gst_type_find_peek (tf, offset, 5); + data_scan_ctx_advance (tf, &c, 1); } } -- 2.7.4