adx: add an ADX parser.

This simplifies the decoder so it doesn't have to process an in-packet header
or handle arbitrary-sized packets. It also fixes decoding of files with large
headers.

libavcodec/adx_parser.c

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2011  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
+ * ADX audio parser
+ *
+ * Reads header to extradata and splits packets into individual blocks.
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "parser.h"
+#include "adx.h"
+
+typedef struct ADXParseContext {
+    ParseContext pc;
+    int header_size;
+    int block_size;
+    int buf_pos;
+} ADXParseContext;
+
+#define MIN_HEADER_SIZE 24
+
+static int adx_parse(AVCodecParserContext *s1,
+                           AVCodecContext *avctx,
+                           const uint8_t **poutbuf, int *poutbuf_size,
+                           const uint8_t *buf, int buf_size)
+{
+    ADXParseContext *s = s1->priv_data;
+    ParseContext *pc = &s->pc;
+    int next = END_NOT_FOUND;
+
+    if (!avctx->extradata_size) {
+        int ret;
+
+        ff_combine_frame(pc, END_NOT_FOUND, &buf, &buf_size);
+
+        if (!s->header_size && pc->index >= MIN_HEADER_SIZE) {
+            if (ret = ff_adx_decode_header(avctx, pc->buffer, pc->index,
+                                           &s->header_size, NULL))
+                return AVERROR_INVALIDDATA;
+            s->block_size = BLOCK_SIZE * avctx->channels;
+        }
+        if (s->header_size && s->header_size <= pc->index) {
+            avctx->extradata = av_mallocz(s->header_size + FF_INPUT_BUFFER_PADDING_SIZE);
+            if (!avctx->extradata)
+                return AVERROR(ENOMEM);
+            avctx->extradata_size = s->header_size;
+            memcpy(avctx->extradata, pc->buffer, s->header_size);
+            memmove(pc->buffer, pc->buffer + s->header_size, s->header_size);
+            pc->index -= s->header_size;
+        }
+        *poutbuf      = NULL;
+        *poutbuf_size = 0;
+        return buf_size;
+    }
+
+    if (pc->index - s->buf_pos >= s->block_size) {
+        *poutbuf      = &pc->buffer[s->buf_pos];
+        *poutbuf_size = s->block_size;
+        s->buf_pos   += s->block_size;
+        return 0;
+    }
+    if (pc->index && s->buf_pos) {
+        memmove(pc->buffer, &pc->buffer[s->buf_pos], pc->index - s->buf_pos);
+        pc->index -= s->buf_pos;
+        s->buf_pos = 0;
+    }
+    if (buf_size + pc->index >= s->block_size)
+        next = s->block_size - pc->index;
+
+    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_adx_parser = {
+    .codec_ids      = { CODEC_ID_ADPCM_ADX },
+    .priv_data_size = sizeof(ADXParseContext),
+    .parser_parse   = adx_parse,
+    .parser_close   = ff_parse_close,
+};