static int ws_snd_decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt) { WSSndContext *s = avctx->priv_data; const uint8_t *buf = avpkt->data; int buf_size = avpkt->size; int in_size, out_size, ret; int sample = 128; uint8_t *samples; 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 (in_size > buf_size) { av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n"); return -1; } /* get output buffer */ s->frame.nb_samples = out_size; if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) { av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); return ret; } samples = s->frame.data[0]; samples_end = samples + out_size; if (in_size == out_size) { memcpy(samples, buf, out_size); *got_frame_ptr = 1; *(AVFrame *)data = s->frame; 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 += ( code & 0x3) - 2; sample = av_clip_uint8(sample); *samples++ = sample; sample += ((code >> 2) & 0x3) - 2; sample = av_clip_uint8(sample); *samples++ = sample; sample += ((code >> 4) & 0x3) - 2; sample = av_clip_uint8(sample); *samples++ = sample; sample += (code >> 6) - 2; 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 */ memcpy(samples, buf, smp); samples += smp; buf += smp; sample = buf[-1]; } break; default: /* run */ memset(samples, sample, smp); samples += smp; } } s->frame.nb_samples = samples - s->frame.data[0]; *got_frame_ptr = 1; *(AVFrame *)data = s->frame; return buf_size; }