static int ws_snd_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) { const uint8_t *buf = avpkt->data; int buf_size = avpkt->size; // WSSNDContext *c = avctx->priv_data; int in_size, out_size; int sample = 128; int i; uint8_t *samples = data; if (!buf_size) return 0; out_size = AV_RL16(&buf[0]); in_size = AV_RL16(&buf[2]); buf += 4; if (out_size > *data_size) { av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n"); return -1; } if (in_size > buf_size) { av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n"); return -1; } *data_size = out_size; if (in_size == out_size) { for (i = 0; i < out_size; i++) *samples++ = *buf++; return buf_size; } while (out_size > 0) { int code; uint8_t count; code = (*buf) >> 6; count = (*buf) & 0x3F; buf++; switch(code) { case 0: /* ADPCM 2-bit */ for (count++; count > 0; count--) { code = *buf++; sample += ws_adpcm_2bit[code & 0x3]; sample = av_clip_uint8(sample); *samples++ = sample; sample += ws_adpcm_2bit[(code >> 2) & 0x3]; sample = av_clip_uint8(sample); *samples++ = sample; sample += ws_adpcm_2bit[(code >> 4) & 0x3]; sample = av_clip_uint8(sample); *samples++ = sample; sample += ws_adpcm_2bit[(code >> 6) & 0x3]; sample = av_clip_uint8(sample); *samples++ = sample; out_size -= 4; } break; case 1: /* ADPCM 4-bit */ for (count++; count > 0; count--) { code = *buf++; sample += ws_adpcm_4bit[code & 0xF]; sample = av_clip_uint8(sample); *samples++ = sample; sample += ws_adpcm_4bit[code >> 4]; sample = av_clip_uint8(sample); *samples++ = sample; out_size -= 2; } break; case 2: /* no compression */ if (count & 0x20) { /* big delta */ int8_t t; t = count; t <<= 3; sample += t >> 3; sample = av_clip_uint8(sample); *samples++ = sample; out_size--; } else { /* copy */ for (count++; count > 0; count--) { *samples++ = *buf++; out_size--; } sample = buf[-1]; } break; default: /* run */ for(count++; count > 0; count--) { *samples++ = sample; out_size--; } } } return buf_size; }