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typefinding: extend AAC typefinder to detect LOAS streams

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Extend AAC typefinder to recognize LOAS stream as specified by
ISO/IEC 14496-3:2009.

https://bugzilla.gnome.org/show_bug.cgi?id=623918
This commit is contained in:
Andrzej K. Haczewski 2010-07-08 15:22:08 +02:00 committed by Tim-Philipp Müller
parent 2a00fefd2a
commit 6c5cee1d02
1 changed files with 43 additions and 2 deletions
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45
gst/typefind/gsttypefindfunctions.c
View file

@ -671,6 +671,8 @@ aac_type_find (GstTypeFind * tf, gpointer unused)
* again a valid syncpoint on the next one (28 bits) for certainty. We
* require 4 kB, which is quite a lot, since frames are generally 200-400
* bytes.
* LOAS has 2 possible syncwords, which are 11 bits and 16 bits long.
* The following stream syntax depends on which one is found.
*/
if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 6)))
break;
@ -743,6 +745,45 @@ aac_type_find (GstTypeFind * tf, gpointer unused)
break;
}
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;
}
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;
}
/* 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);
gst_type_find_suggest_simple (tf, GST_TYPE_FIND_LIKELY, "audio/mpeg",
"framed", G_TYPE_BOOLEAN, FALSE,
"mpegversion", G_TYPE_INT, 4,
"stream-format", G_TYPE_STRING, "loas", NULL);
break;
}
GST_DEBUG ("No next frame found... (should have been at 0x%x)", len);
} else if (!memcmp (c.data, "ADIF", 4)) {
/* ADIF header */
@ -3966,7 +4007,7 @@ plugin_init (GstPlugin * plugin)
static const gchar *compress_exts[] = { "Z", NULL };
static const gchar *m4a_exts[] = { "m4a", NULL };
static const gchar *q3gp_exts[] = { "3gp", NULL };
static const gchar *aac_exts[] = { "aac", NULL };
static const gchar *aac_exts[] = { "aac", "adts", "adif", "loas", NULL };
static const gchar *spc_exts[] = { "spc", NULL };
static const gchar *wavpack_exts[] = { "wv", "wvp", NULL };
static const gchar *wavpack_correction_exts[] = { "wvc", NULL };
@ -4199,7 +4240,7 @@ plugin_init (GstPlugin * plugin)
NULL, CMML_CAPS, NULL, NULL);
TYPE_FIND_REGISTER_START_WITH (plugin, "application/x-executable",
GST_RANK_MARGINAL, NULL, "\177ELF", 4, GST_TYPE_FIND_MAXIMUM);
TYPE_FIND_REGISTER (plugin, "adts_mpeg_stream", GST_RANK_SECONDARY,
TYPE_FIND_REGISTER (plugin, "aac", GST_RANK_SECONDARY,
aac_type_find, aac_exts, AAC_CAPS, NULL, NULL);
TYPE_FIND_REGISTER_START_WITH (plugin, "audio/x-spc", GST_RANK_SECONDARY,
spc_exts, "SNES-SPC700 Sound File Data", 27, GST_TYPE_FIND_MAXIMUM);