Maxis XA demuxer and decoder.

Patch by Robert Marston rmarston (\at/) gmail point com
Original thread: [FFmpeg-soc] [Patch] Maxis EA XA decoder - GSoC Task
Date: 04/08/2008 01:36 AM

Originally committed as revision 12817 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/adpcm.c

@@ -34,6 +34,7 @@
  * EA IMA EACS decoder by Peter Ross (pross@xvid.org)
  * EA IMA SEAD decoder by Peter Ross (pross@xvid.org)
  * EA ADPCM XAS decoder by Peter Ross (pross@xvid.org)
+ * MAXIS EA ADPCM decoder by Robert Marston (rmarston@gmail.com)
  * THP ADPCM decoder by Marco Gerards (mgerards@xs4all.nl)
  *
  * Features and limitations:
@@ -666,7 +667,7 @@ static int adpcm_encode_frame(AVCodecContext *avctx,
 static av_cold int adpcm_decode_init(AVCodecContext * avctx)
 {
     ADPCMContext *c = avctx->priv_data;
-    unsigned int max_channels = 2;
+    unsigned int max_channels = 2, channel;
 
     switch(avctx->codec->id) {
     case CODEC_ID_ADPCM_EA_R1:
@@ -900,6 +901,7 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
     int32_t coeff1l, coeff2l, coeff1r, coeff2r;
     uint8_t shift_left, shift_right;
     int count1, count2;
+    int coeff[2][2], shift[2];//used in EA MAXIS ADPCM
 
     if (!buf_size)
         return 0;
@@ -1235,6 +1237,28 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
             }
         }
         break;
+    case CODEC_ID_ADPCM_EA_MAXIS_XA:
+        for(channel = 0; channel < avctx->channels; channel++) {
+            for (i=0; i<2; i++)
+                coeff[channel][i] = ea_adpcm_table[(*src >> 4) + 4*i];
+            shift[channel] = (*src & 0x0F) + 8;
+            src++;
+        }
+        for (count1 = 0; count1 < (buf_size - avctx->channels) / avctx->channels; count1++) {
+            for(i = 4; i >= 0; i-=4) { /* Pairwise samples LL RR (st) or LL LL (mono) */
+                for(channel = 0; channel < avctx->channels; channel++) {
+                    int32_t sample = (int32_t)(((*(src+channel) >> i) & 0x0F) << 0x1C) >> shift[channel];
+                    sample = (sample +
+                             c->status[channel].sample1 * coeff[channel][0] +
+                             c->status[channel].sample2 * coeff[channel][1] + 0x80) >> 8;
+                    c->status[channel].sample2 = c->status[channel].sample1;
+                    c->status[channel].sample1 = av_clip_int16(sample);
+                    *samples++ = c->status[channel].sample1;
+                }
+            }
+            src+=avctx->channels;
+        }
+        break;
     case CODEC_ID_ADPCM_EA_R1:
     case CODEC_ID_ADPCM_EA_R2:
     case CODEC_ID_ADPCM_EA_R3: {
@@ -1613,6 +1637,7 @@ ADPCM_ENCODER(id,name) ADPCM_DECODER(id,name)
 ADPCM_DECODER(CODEC_ID_ADPCM_4XM, adpcm_4xm);
 ADPCM_DECODER(CODEC_ID_ADPCM_CT, adpcm_ct);
 ADPCM_DECODER(CODEC_ID_ADPCM_EA, adpcm_ea);
+ADPCM_DECODER(CODEC_ID_ADPCM_EA_MAXIS_XA, adpcm_ea_maxis_xa);
 ADPCM_DECODER(CODEC_ID_ADPCM_EA_R1, adpcm_ea_r1);
 ADPCM_DECODER(CODEC_ID_ADPCM_EA_R2, adpcm_ea_r2);
 ADPCM_DECODER(CODEC_ID_ADPCM_EA_R3, adpcm_ea_r3);

libavcodec/allcodecs.c

@@ -244,6 +244,7 @@ void avcodec_register_all(void)
     REGISTER_ENCDEC  (ADPCM_ADX, adpcm_adx);
     REGISTER_DECODER (ADPCM_CT, adpcm_ct);
     REGISTER_DECODER (ADPCM_EA, adpcm_ea);
+    REGISTER_DECODER (ADPCM_EA_MAXIS_XA, adpcm_ea_maxis_xa);
     REGISTER_DECODER (ADPCM_EA_R1, adpcm_ea_r1);
     REGISTER_DECODER (ADPCM_EA_R2, adpcm_ea_r2);
     REGISTER_DECODER (ADPCM_EA_R3, adpcm_ea_r3);

libavcodec/avcodec.h

@@ -235,6 +235,7 @@ enum CodecID {
     CODEC_ID_ADPCM_IMA_EA_SEAD,
     CODEC_ID_ADPCM_IMA_EA_EACS,
     CODEC_ID_ADPCM_EA_XAS,
+    CODEC_ID_ADPCM_EA_MAXIS_XA,
 
     /* AMR */
     CODEC_ID_AMR_NB= 0x12000,

libavformat/Makefile

@@ -180,6 +180,7 @@ OBJS-$(CONFIG_WC3_DEMUXER)               += wc3movie.o
 OBJS-$(CONFIG_WSAUD_DEMUXER)             += westwood.o
 OBJS-$(CONFIG_WSVQA_DEMUXER)             += westwood.o
 OBJS-$(CONFIG_WV_DEMUXER)                += wv.o
+OBJS-$(CONFIG_XA_DEMUXER)                += xa.o
 OBJS-$(CONFIG_YUV4MPEGPIPE_MUXER)        += yuv4mpeg.o
 OBJS-$(CONFIG_YUV4MPEGPIPE_DEMUXER)      += yuv4mpeg.o
 

libavformat/allformats.c

@@ -170,6 +170,7 @@ void av_register_all(void)
     REGISTER_DEMUXER  (WSAUD, wsaud);
     REGISTER_DEMUXER  (WSVQA, wsvqa);
     REGISTER_DEMUXER  (WV, wv);
+    REGISTER_DEMUXER  (XA, xa);
     REGISTER_MUXDEMUX (YUV4MPEGPIPE, yuv4mpegpipe);
 
     /* external libraries */

libavformat/xa.c

@@ -0,0 +1,116 @@
+/*
+ * Maxis XA (.xa) File Demuxer
+ * Copyright (c) 2008 Robert Marston
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file xa.c
+ * Maxis XA File Demuxer
+ * by Robert Marston (rmarston@gmail.com)
+ * for more information on the XA audio format see
+ *   http://wiki.multimedia.cx/index.php?title=Maxis_XA
+ */
+
+#include "avformat.h"
+
+#define XA00_TAG MKTAG('X', 'A', 0, 0)
+#define XAI0_TAG MKTAG('X', 'A', 'I', 0)
+#define XAJ0_TAG MKTAG('X', 'A', 'J', 0)
+
+typedef struct MaxisXADemuxContext {
+    uint32_t out_size;
+    uint32_t sent_bytes;
+    uint32_t audio_frame_counter;
+} MaxisXADemuxContext;
+
+static int xa_probe(AVProbeData *p)
+{
+    switch(AV_RL32(p->buf)) {
+    case XA00_TAG:
+    case XAI0_TAG:
+    case XAJ0_TAG:
+        return AVPROBE_SCORE_MAX;
+    }
+    return 0;
+}
+
+static int xa_read_header(AVFormatContext *s,
+               AVFormatParameters *ap)
+{
+    MaxisXADemuxContext *xa = s->priv_data;
+    ByteIOContext *pb = s->pb;
+    AVStream *st;
+
+    /*Set up the XA Audio Decoder*/
+    st = av_new_stream(s, 0);
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    st->codec->codec_type   = CODEC_TYPE_AUDIO;
+    st->codec->codec_id     = CODEC_ID_ADPCM_EA_MAXIS_XA;
+    url_fskip(pb, 4);       /* Skip the XA ID */
+    xa->out_size            =  get_le32(pb);
+    url_fskip(pb, 2);       /* Skip the tag */
+    st->codec->channels     = get_le16(pb);
+    st->codec->sample_rate  = get_le32(pb);
+    /* Value in file is average byte rate*/
+    st->codec->bit_rate     = get_le32(pb) * 8;
+    st->codec->block_align  = get_le16(pb);
+    st->codec->bits_per_sample = get_le16(pb);
+
+    av_set_pts_info(st, 64, 1, st->codec->sample_rate);
+
+    return 0;
+}
+
+static int xa_read_packet(AVFormatContext *s,
+                          AVPacket *pkt)
+{
+    MaxisXADemuxContext *xa = s->priv_data;
+    AVStream *st = s->streams[0];
+    ByteIOContext *pb = s->pb;
+    unsigned int packet_size;
+    int ret;
+
+    if(xa->sent_bytes > xa->out_size)
+        return AVERROR(EIO);
+    /* 1 byte header and 14 bytes worth of samples * number channels per block */
+    packet_size = 15*st->codec->channels;
+
+    ret = av_get_packet(pb, pkt, packet_size);
+    if(ret != packet_size)
+        return AVERROR(EIO);
+
+    pkt->stream_index = st->index;
+    xa->sent_bytes += packet_size;
+    pkt->pts = xa->audio_frame_counter;
+    /* 14 bytes Samples per channel with 2 samples per byte */
+    xa->audio_frame_counter += 28 * st->codec->channels;
+
+    return ret;
+}
+
+AVInputFormat xa_demuxer = {
+    "xa",
+    "Maxis XA File Format",
+    sizeof(MaxisXADemuxContext),
+    xa_probe,
+    xa_read_header,
+    xa_read_packet,
+};