FFmpeg: libavcodec/adxdec.c Source File

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libavcodec

adxdec.c

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1 /*

2 * ADX ADPCM codecs

4 *

5 * This file is part of FFmpeg.

6 *

7 * FFmpeg is free software; you can redistribute it and/or

8 * modify it under the terms of the GNU Lesser General Public

9 * License as published by the Free Software Foundation; either

10 * version 2.1 of the License, or (at your option) any later version.

11 *

12 * FFmpeg is distributed in the hope that it will be useful,

13 * but WITHOUT ANY WARRANTY; without even the implied warranty of

14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

15 * Lesser General Public License for more details.

16 *

17 * You should have received a copy of the GNU Lesser General Public

18 * License along with FFmpeg; if not, write to the Free Software

19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

20 */

22 #include "libavutil/intreadwrite.h"

23 #include "avcodec.h"

24 #include "adx.h"

25 #include "get_bits.h"

26 #include "internal.h"

28 /**

29 * @file

30 * SEGA CRI adx codecs.

31 *

32 * Reference documents:

33 * http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html

34 * adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/

35 */

37 static av_cold int adx_decode_init(AVCodecContext *avctx)

38 {

39 ADXContext *c = avctx->priv_data;

40 int ret, header_size;

42 if (avctx->extradata_size >= 24) {

43 if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,

44 avctx->extradata_size, &header_size,

45 c->coeff)) < 0) {

46 av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");

47 return AVERROR_INVALIDDATA;

48 }

49 c->channels = avctx->channels;

50 c->header_parsed = 1;

51 }

53 avctx->sample_fmt = AV_SAMPLE_FMT_S16P;

55 return 0;

56 }

58 /**

59 * Decode 32 samples from 18 bytes.

60 *

61 * A 16-bit scalar value is applied to 32 residuals, which then have a

62 * 2nd-order LPC filter applied to it to form the output signal for a single

63 * channel.

64 */

65 static int adx_decode(ADXContext *c, int16_t *out, int offset,

66 const uint8_t *in, int ch)

67 {

68 ADXChannelState *prev = &c->prev[ch];

69 GetBitContext gb;

70 int scale = AV_RB16(in);

71 int i;

72 int s0, s1, s2, d;

74 /* check if this is an EOF packet */

75 if (scale & 0x8000)

76 return -1;

78 init_get_bits(&gb, in + 2, (BLOCK_SIZE - 2) * 8);

79 out += offset;

80 s1 = prev->s1;

81 s2 = prev->s2;

82 for (i = 0; i < BLOCK_SAMPLES; i++) {

83 d = get_sbits(&gb, 4);

84 s0 = ((d << COEFF_BITS) * scale + c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS;

85 s2 = s1;

86 s1 = av_clip_int16(s0);

87 *out++ = s1;

88 }

89 prev->s1 = s1;

90 prev->s2 = s2;

92 return 0;

93 }

95 static int adx_decode_frame(AVCodecContext *avctx, void *data,

96 int *got_frame_ptr, AVPacket *avpkt)

97 {

98 AVFrame *frame = data;

99 int buf_size = avpkt->size;

100 ADXContext *c = avctx->priv_data;

101 int16_t **samples;

102 int samples_offset;

103 const uint8_t *buf = avpkt->data;

104 const uint8_t *buf_end = buf + avpkt->size;

105 int num_blocks, ch, ret;

106

107 if (c->eof) {

108 *got_frame_ptr = 0;

109 return buf_size;

110 }

111

112 if (!c->header_parsed && buf_size >= 2 && AV_RB16(buf) == 0x8000) {

113 int header_size;

114 if ((ret = avpriv_adx_decode_header(avctx, buf, buf_size, &header_size,

115 c->coeff)) < 0) {

116 av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");

117 return AVERROR_INVALIDDATA;

118 }

119 c->channels = avctx->channels;

120 c->header_parsed = 1;

121 if (buf_size < header_size)

122 return AVERROR_INVALIDDATA;

123 buf += header_size;

124 buf_size -= header_size;

125 }

126 if (!c->header_parsed)

127 return AVERROR_INVALIDDATA;

128

129 /* calculate number of blocks in the packet */

130 num_blocks = buf_size / (BLOCK_SIZE * c->channels);

131

132 /* if the packet is not an even multiple of BLOCK_SIZE, check for an EOF

133 packet */

134 if (!num_blocks || buf_size % (BLOCK_SIZE * avctx->channels)) {

135 if (buf_size >= 4 && (AV_RB16(buf) & 0x8000)) {

136 c->eof = 1;

137 *got_frame_ptr = 0;

138 return avpkt->size;

139 }

140 return AVERROR_INVALIDDATA;

141 }

142

143 /* get output buffer */

144 frame->nb_samples = num_blocks * BLOCK_SAMPLES;

145 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

146 return ret;

147 samples = (int16_t **)frame->extended_data;

148 samples_offset = 0;

149

150 while (num_blocks--) {

151 for (ch = 0; ch < c->channels; ch++) {

152 if (buf_end - buf < BLOCK_SIZE || adx_decode(c, samples[ch], samples_offset, buf, ch)) {

153 c->eof = 1;

154 buf = avpkt->data + avpkt->size;

155 break;

156 }

157 buf_size -= BLOCK_SIZE;

158 buf += BLOCK_SIZE;

159 }

160 samples_offset += BLOCK_SAMPLES;

161 }

162

163 *got_frame_ptr = 1;

164

165 return buf - avpkt->data;

166 }

167

168 static void adx_decode_flush(AVCodecContext *avctx)

169 {

170 ADXContext *c = avctx->priv_data;

171 memset(c->prev, 0, sizeof(c->prev));

172 c->eof = 0;

173 }

174

175 AVCodec ff_adpcm_adx_decoder = {

176 .name = "adpcm_adx",

177 .type = AVMEDIA_TYPE_AUDIO,

178 .id = AV_CODEC_ID_ADPCM_ADX,

179 .priv_data_size = sizeof(ADXContext),

180 .init = adx_decode_init,

181 .decode = adx_decode_frame,

182 .flush = adx_decode_flush,

183 .capabilities = CODEC_CAP_DR1,

184 .long_name = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),

185 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,

186 AV_SAMPLE_FMT_NONE },

187 };

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