FFmpeg: libavcodec/s302menc.c Source File

FFmpeg

[フレーム]

libavcodec

s302menc.c

Go to the documentation of this file.

1 /*

2 * SMPTE 302M encoder

5 *

6 * This file is part of FFmpeg.

7 *

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

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

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

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

12 *

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

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

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

16 * Lesser General Public License for more details.

17 *

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

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

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

21 */

23 #include "avcodec.h"

24 #include "internal.h"

25 #include "mathops.h"

26 #include "put_bits.h"

28 #define AES3_HEADER_LEN 4

30 typedef struct S302MEncContext {

31 uint8_t framing_index; /* Set for even channels on multiple of 192 samples */

32 } S302MEncContext;

34 static av_cold int s302m_encode_init(AVCodecContext *avctx)

35 {

36 S302MEncContext *s = avctx->priv_data;

38 if (avctx->channels & 1 || avctx->channels > 8) {

39 av_log(avctx, AV_LOG_ERROR,

40 "Encoding %d channel(s) is not allowed. Only 2, 4, 6 and 8 channels are supported.\n",

41 avctx->channels);

42 return AVERROR(EINVAL);

43 }

45 switch (avctx->sample_fmt) {

46 case AV_SAMPLE_FMT_S16:

47 avctx->bits_per_raw_sample = 16;

48 break;

49 case AV_SAMPLE_FMT_S32:

50 if (avctx->bits_per_raw_sample > 20) {

51 if (avctx->bits_per_raw_sample > 24)

52 av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");

53 avctx->bits_per_raw_sample = 24;

54 } else if (!avctx->bits_per_raw_sample) {

55 avctx->bits_per_raw_sample = 24;

56 } else if (avctx->bits_per_raw_sample <= 20) {

57 avctx->bits_per_raw_sample = 20;

58 }

59 }

61 avctx->frame_size = 0;

62 avctx->bit_rate = 48000 * avctx->channels *

63 (avctx->bits_per_raw_sample + 4);

64 s->framing_index = 0;

66 return 0;

67 }

69 static int s302m_encode2_frame(AVCodecContext *avctx, AVPacket *avpkt,

70 const AVFrame *frame, int *got_packet_ptr)

71 {

72 S302MEncContext *s = avctx->priv_data;

73 const int buf_size = AES3_HEADER_LEN +

74 (frame->nb_samples *

75 avctx->channels *

76 (avctx->bits_per_raw_sample + 4)) / 8;

77 int ret, c, channels;

78 uint8_t *o;

79 PutBitContext pb;

81 if ((ret = ff_alloc_packet2(avctx, avpkt, buf_size)) < 0)

82 return ret;

84 o = avpkt->data;

85 init_put_bits(&pb, o, buf_size);

86 put_bits(&pb, 16, buf_size - AES3_HEADER_LEN);

87 put_bits(&pb, 2, (avctx->channels - 2) >> 1); // number of channels

88 put_bits(&pb, 8, 0); // channel ID

89 put_bits(&pb, 2, (avctx->bits_per_raw_sample - 16) / 4); // bits per samples (0 = 16bit, 1 = 20bit, 2 = 24bit)

90 put_bits(&pb, 4, 0); // alignments

91 flush_put_bits(&pb);

92 o += AES3_HEADER_LEN;

94 if (avctx->bits_per_raw_sample == 24) {

95 const uint32_t *samples = (uint32_t *)frame->data[0];

97 for (c = 0; c < frame->nb_samples; c++) {

98 uint8_t vucf = s->framing_index == 0 ? 0x10: 0;

100 for (channels = 0; channels < avctx->channels; channels += 2) {

101 o[0] = ff_reverse[(samples[0] & 0x0000FF00) >> 8];

102 o[1] = ff_reverse[(samples[0] & 0x00FF0000) >> 16];

103 o[2] = ff_reverse[(samples[0] & 0xFF000000) >> 24];

104 o[3] = ff_reverse[(samples[1] & 0x00000F00) >> 4] | vucf;

105 o[4] = ff_reverse[(samples[1] & 0x000FF000) >> 12];

106 o[5] = ff_reverse[(samples[1] & 0x0FF00000) >> 20];

107 o[6] = ff_reverse[(samples[1] & 0xF0000000) >> 28];

108 o += 7;

109 samples += 2;

110 }

111

112 s->framing_index++;

113 if (s->framing_index >= 192)

114 s->framing_index = 0;

115 }

116 } else if (avctx->bits_per_raw_sample == 20) {

117 const uint32_t *samples = (uint32_t *)frame->data[0];

118

119 for (c = 0; c < frame->nb_samples; c++) {

120 uint8_t vucf = s->framing_index == 0 ? 0x80: 0;

121

122 for (channels = 0; channels < avctx->channels; channels += 2) {

123 o[0] = ff_reverse[ (samples[0] & 0x000FF000) >> 12];

124 o[1] = ff_reverse[ (samples[0] & 0x0FF00000) >> 20];

125 o[2] = ff_reverse[((samples[0] & 0xF0000000) >> 28) | vucf];

126 o[3] = ff_reverse[ (samples[1] & 0x000FF000) >> 12];

127 o[4] = ff_reverse[ (samples[1] & 0x0FF00000) >> 20];

128 o[5] = ff_reverse[ (samples[1] & 0xF0000000) >> 28];

129 o += 6;

130 samples += 2;

131 }

132

133 s->framing_index++;

134 if (s->framing_index >= 192)

135 s->framing_index = 0;

136 }

137 } else if (avctx->bits_per_raw_sample == 16) {

138 const uint16_t *samples = (uint16_t *)frame->data[0];

139

140 for (c = 0; c < frame->nb_samples; c++) {

141 uint8_t vucf = s->framing_index == 0 ? 0x10 : 0;

142

143 for (channels = 0; channels < avctx->channels; channels += 2) {

144 o[0] = ff_reverse[ samples[0] & 0xFF];

145 o[1] = ff_reverse[(samples[0] & 0xFF00) >> 8];

146 o[2] = ff_reverse[(samples[1] & 0x0F) << 4] | vucf;

147 o[3] = ff_reverse[(samples[1] & 0x0FF0) >> 4];

148 o[4] = ff_reverse[(samples[1] & 0xF000) >> 12];

149 o += 5;

150 samples += 2;

151

152 }

153

154 s->framing_index++;

155 if (s->framing_index >= 192)

156 s->framing_index = 0;

157 }

158 }

159

160 *got_packet_ptr = 1;

161

162 return 0;

163 }

164

165 AVCodec ff_s302m_encoder = {

166 .name = "s302m",

167 .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),

168 .type = AVMEDIA_TYPE_AUDIO,

169 .id = AV_CODEC_ID_S302M,

170 .priv_data_size = sizeof(S302MEncContext),

171 .init = s302m_encode_init,

172 .encode2 = s302m_encode2_frame,

173 .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32,

174 AV_SAMPLE_FMT_S16,

175 AV_SAMPLE_FMT_NONE },

176 .capabilities = CODEC_CAP_VARIABLE_FRAME_SIZE | CODEC_CAP_EXPERIMENTAL,

177 .supported_samplerates = (const int[]) { 48000, 0 },

178 };

Generated on Sun Mar 8 2015 02:34:59 for FFmpeg by doxygen 1.8.2