added dummy crc output format for easy codec testing

Originally committed as revision 525 to svn://svn.ffmpeg.org/ffmpeg/trunk

libav/crc.c

+/* 
+ * CRC decoder (for codec/format testing)
+ * Copyright (c) 2002 Gerard Lantau.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include "avformat.h"
+
+/* adler32.c -- compute the Adler-32 checksum of a data stream
+ * Copyright (C) 1995 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#define BASE 65521L /* largest prime smaller than 65536 */
+#define NMAX 5552
+/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
+
+#define DO1(buf)  {s1 += *buf++; s2 += s1;}
+#define DO2(buf)  DO1(buf); DO1(buf);
+#define DO4(buf)  DO2(buf); DO2(buf);
+#define DO8(buf)  DO4(buf); DO4(buf);
+#define DO16(buf) DO8(buf); DO8(buf);
+
+static UINT32 adler32(UINT32 adler, UINT8 *buf, unsigned int len)
+{
+    unsigned long s1 = adler & 0xffff;
+    unsigned long s2 = (adler >> 16) & 0xffff;
+    int k;
+
+    if (buf == NULL) return 1L;
+
+    while (len > 0) {
+        k = len < NMAX ? len : NMAX;
+        len -= k;
+        while (k >= 16) {
+            DO16(buf);
+            k -= 16;
+        }
+        if (k != 0) do {
+            DO1(buf);
+        } while (--k);
+        s1 %= BASE;
+        s2 %= BASE;
+    }
+    return (s2 << 16) | s1;
+}
+
+typedef struct CRCState {
+    UINT32 crcval;
+} CRCState;
+
+/* simple formats */
+static int crc_write_header(struct AVFormatContext *s)
+{
+    CRCState *crc;
+    crc = av_malloc(sizeof(CRCState));
+    if (!crc)
+        return -1;
+    s->priv_data = crc;
+    
+    /* init CRC */
+    crc->crcval = adler32(0, NULL, 0);
+
+    return 0;
+}
+
+static int crc_write_packet(struct AVFormatContext *s, 
+                            int stream_index,
+                            unsigned char *buf, int size, int force_pts)
+{
+    CRCState *crc = s->priv_data;
+    crc->crcval = adler32(crc->crcval, buf, size);
+    return 0;
+}
+
+static int crc_write_trailer(struct AVFormatContext *s)
+{
+    CRCState *crc = s->priv_data;
+    char buf[64];
+
+    snprintf(buf, sizeof(buf), "CRC=%08x\n", crc->crcval);
+    put_buffer(&s->pb, buf, strlen(buf));
+    put_flush_packet(&s->pb);
+    return 0;
+}
+
+AVFormat crc_format = {
+    "crc",
+    "crc testing format",
+    NULL,
+    "",
+    CODEC_ID_PCM_S16LE,
+    CODEC_ID_RAWVIDEO,
+    crc_write_header,
+    crc_write_packet,
+    crc_write_trailer,
+};