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; uint8_t *samples_end; if (!buf_size) return 0; if (buf_size < 4) { av_log(avctx, AV_LOG_ERROR, "packet is too small\n"); return AVERROR(EINVAL); } 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; } samples_end = samples + out_size; if (in_size == out_size) { for (i = 0; i < out_size; i++) *samples++ = *buf++; *data_size = out_size; return buf_size; } while (samples < samples_end && buf - avpkt->data < buf_size) { int code, smp, size; uint8_t count; code = (*buf) >> 6; count = (*buf) & 0x3F; buf++; /* make sure we don't write past the output buffer */ switch (code) { case 0: smp = 4; break; case 1: smp = 2; break; case 2: smp = (count & 0x20) ? 1 : count + 1; break; default: smp = count + 1; break; } if (samples_end - samples < smp) break; /* make sure we don't read past the input buffer */ size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1; if ((buf - avpkt->data) + size > buf_size) break; 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; } 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; } 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; } else { /* copy */ for (count++; count > 0; count--) { *samples++ = *buf++; } sample = buf[-1]; } break; default: /* run */ for(count++; count > 0; count--) { *samples++ = sample; } } } *data_size = samples - (uint8_t *)data; return buf_size; }