avcodec: add GSM parser

The WAVE demuxer returns packets with many blocks per frame, which needs to be
parsed into single blocks. This has a side-effect of fixing the timestamps.

1 files changed, 79 insertions, 0 deletions

diff --git a/libavcodec/gsm_parser.c b/libavcodec/gsm_parser.c
new file mode 100644
index 0000000000..a2965d3fb5
--- /dev/null
+++ b/libavcodec/gsm_parser.c
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2012  Justin Ruggles
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * GSM audio parser
+ *
+ * Splits packets into individual blocks.
+ */
+
+#include "parser.h"
+#include "gsm.h"
+
+typedef struct GSMParseContext {
+    ParseContext pc;
+    int block_size;
+    int remaining;
+} GSMParseContext;
+
+static int gsm_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
+                     const uint8_t **poutbuf, int *poutbuf_size,
+                     const uint8_t *buf, int buf_size)
+{
+    GSMParseContext *s = s1->priv_data;
+    ParseContext *pc = &s->pc;
+    int next;
+
+    if (!s->block_size) {
+        switch (avctx->codec_id) {
+        case CODEC_ID_GSM:    s->block_size = GSM_BLOCK_SIZE;    break;
+        case CODEC_ID_GSM_MS: s->block_size = GSM_MS_BLOCK_SIZE; break;
+        default:
+            return AVERROR(EINVAL);
+        }
+    }
+
+    if (!s->remaining)
+        s->remaining = s->block_size;
+    if (s->remaining <= buf_size) {
+        next = s->remaining;
+        s->remaining = 0;
+    } else {
+        next = END_NOT_FOUND;
+        s->remaining -= buf_size;
+    }
+
+    if (ff_combine_frame(pc, next, &buf, &buf_size) < 0 || !buf_size) {
+        *poutbuf      = NULL;
+        *poutbuf_size = 0;
+        return buf_size;
+    }
+    *poutbuf      = buf;
+    *poutbuf_size = buf_size;
+    return next;
+}
+
+AVCodecParser ff_gsm_parser = {
+    .codec_ids      = { CODEC_ID_GSM, CODEC_ID_GSM_MS },
+    .priv_data_size = sizeof(GSMParseContext),
+    .parser_parse   = gsm_parse,
+    .parser_close   = ff_parse_close,
+};