From: Tim-Philipp Müller Date: Sun, 11 Nov 2012 16:33:32 +0000 (+0000) Subject: typefinding: improve AAC LOAS typefinding X-Git-Tag: 1.19.3~511^2~5749 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=61f04f1460922482cd28e8d22bead8e90dd53431;p=platform%2Fupstream%2Fgstreamer.git typefinding: improve AAC LOAS typefinding Make AAC LOAS typefinding a bit more reliable; don't report a LIKELY probability already after just two sync points, but scan for a few more consecutive frames and determine probability based on how many we found. Fixes mis-detection of wavpack file. https://bugzilla.gnome.org/show_bug.cgi?id=687674 --- diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c index 8b84dca..0b74981 100644 --- a/gst/typefind/gsttypefindfunctions.c +++ b/gst/typefind/gsttypefindfunctions.c @@ -845,6 +845,90 @@ flac_type_find (GstTypeFind * tf, gpointer unused) #endif } +/* TODO: we could probably make a generic function for this.. */ +static gint +aac_type_find_scan_loas_frames_ep (GstTypeFind * tf, DataScanCtx * scan_ctx, + gint max_frames) +{ + DataScanCtx c = *scan_ctx; + guint16 snc; + guint len; + gint count = 0; + + do { + if (!data_scan_ctx_ensure_data (tf, &c, 5)) + break; + + /* EPAudioSyncStream */ + len = ((c.data[2] & 0x0f) << 9) | (c.data[3] << 1) | + ((c.data[4] & 0x80) >> 7); + + if (len == 0 || !data_scan_ctx_ensure_data (tf, &c, len + 2)) { + GST_DEBUG ("Wrong sync or next frame not within reach, len=%u", len); + break; + } + + /* check length of frame */ + snc = GST_READ_UINT16_BE (c.data + len); + if (snc != 0x4de1) { + GST_DEBUG ("No sync found at 0x%" G_GINT64_MODIFIER "x", c.offset + len); + break; + } + + ++count; + + GST_DEBUG ("Found LOAS syncword #%d at offset 0x%" G_GINT64_MODIFIER "x, " + "framelen %u", count, c.offset, len); + + data_scan_ctx_advance (tf, &c, len); + } while (count < max_frames && (c.offset - scan_ctx->offset) < 64 * 1024); + + GST_DEBUG ("found %d consecutive frames", count); + return count; +} + +static gint +aac_type_find_scan_loas_frames (GstTypeFind * tf, DataScanCtx * scan_ctx, + gint max_frames) +{ + DataScanCtx c = *scan_ctx; + guint16 snc; + guint len; + gint count = 0; + + do { + if (!data_scan_ctx_ensure_data (tf, &c, 3)) + break; + + /* AudioSyncStream */ + len = ((c.data[1] & 0x1f) << 8) | c.data[2]; + /* add size of sync stream header */ + len += 3; + + if (len == 0 || !data_scan_ctx_ensure_data (tf, &c, len)) { + GST_DEBUG ("Wrong sync or next frame not within reach, len=%u", len); + break; + } + + /* check length of frame */ + snc = GST_READ_UINT16_BE (c.data + len); + if ((snc & 0xffe0) != 0x56e0) { + GST_DEBUG ("No sync found at 0x%" G_GINT64_MODIFIER "x", c.offset + len); + break; + } + + ++count; + + GST_DEBUG ("Found LOAS syncword #%d at offset 0x%" G_GINT64_MODIFIER "x, " + "framelen %u", count, c.offset, len); + + data_scan_ctx_advance (tf, &c, len); + } while (count < max_frames && (c.offset - scan_ctx->offset) < 64 * 1024); + + GST_DEBUG ("found %d consecutive frames", count); + return count; +} + /*** audio/mpeg version 2, 4 ***/ static GstStaticCaps aac_caps = GST_STATIC_CAPS ("audio/mpeg, " @@ -854,8 +938,10 @@ static GstStaticCaps aac_caps = GST_STATIC_CAPS ("audio/mpeg, " static void aac_type_find (GstTypeFind * tf, gpointer unused) { - /* LUT to convert the AudioObjectType from the ADTS header to a string */ DataScanCtx c = { 0, NULL, 0 }; + GstTypeFindProbability best_probability = GST_TYPE_FIND_NONE; + GstCaps *best_caps = NULL; + guint best_count = 0; while (c.offset < AAC_AMOUNT) { guint snc, len; @@ -941,45 +1027,29 @@ aac_type_find (GstTypeFind * tf, gpointer unused) } GST_DEBUG ("No next frame found... (should have been at 0x%x)", len); - } else if (G_UNLIKELY (((snc & 0xffe0) == 0x56e0) || (snc == 0x4de1))) { - /* LOAS frame */ - - GST_DEBUG ("Found one LOAS syncword at offset 0x%" G_GINT64_MODIFIER - "x, tracing next...", c.offset); - - /* check length of frame for each type of detectable LOAS streams */ - if (snc == 0x4de1) { - /* EPAudioSyncStream */ - len = ((c.data[2] & 0x0f) << 9) | (c.data[3] << 1) | - ((c.data[4] & 0x80) >> 7); - /* add size of EP sync stream header */ - len += 7; - } else { - /* AudioSyncStream */ - len = ((c.data[1] & 0x1f) << 8) | c.data[2]; - /* add size of sync stream header */ - len += 3; - } + } else if (G_UNLIKELY ((snc & 0xffe0) == 0x56e0 || snc == 0x4de1)) { + gint count; - if (len == 0 || !data_scan_ctx_ensure_data (tf, &c, len + 2)) { - GST_DEBUG ("Wrong sync or next frame not within reach, len=%u", len); - goto next; - } + /* LOAS frame */ + GST_INFO ("Possible LOAS syncword at offset 0x%" G_GINT64_MODIFIER + "x, scanning for more frames...", c.offset); - /* check if there's a second LOAS frame */ - snc = GST_READ_UINT16_BE (c.data + len); - if (((snc & 0xffe0) == 0x56e0) || (snc == 0x4de1)) { - GST_DEBUG ("Found second LOAS syncword at offset 0x%" - G_GINT64_MODIFIER "x, framelen %u", c.offset, len); + if (snc == 0x4de1) + count = aac_type_find_scan_loas_frames_ep (tf, &c, 20); + else + count = aac_type_find_scan_loas_frames (tf, &c, 20); - gst_type_find_suggest_simple (tf, GST_TYPE_FIND_LIKELY, "audio/mpeg", + if (count >= 3 && count > best_count) { + gst_caps_unref (best_caps); + best_caps = gst_caps_new_simple ("audio/mpeg", "framed", G_TYPE_BOOLEAN, FALSE, "mpegversion", G_TYPE_INT, 4, "stream-format", G_TYPE_STRING, "loas", NULL); - break; + best_count = count; + best_probability = GST_TYPE_FIND_POSSIBLE - 10 + count * 3; + if (best_probability >= GST_TYPE_FIND_LIKELY) + break; } - - GST_DEBUG ("No next frame found... (should have been at 0x%x)", len); } else if (!memcmp (c.data, "ADIF", 4)) { /* ADIF header */ gst_type_find_suggest_simple (tf, GST_TYPE_FIND_LIKELY, "audio/mpeg", @@ -992,6 +1062,11 @@ aac_type_find (GstTypeFind * tf, gpointer unused) data_scan_ctx_advance (tf, &c, 1); } + + if (best_probability > GST_TYPE_FIND_NONE) { + gst_type_find_suggest (tf, best_probability, best_caps); + gst_caps_unref (best_caps); + } } /*** audio/mpeg version 1 ***/