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apedec: add ability to check CRC 

The CRC flag is only signalled once every few minutes but CRC is still
always present so the patch uses the file version instead.
CRC on 24-bit files wants non-padded samples so skip such files.
Some corrupt samples may have been output before the final check
depending on the -max_samples setting.
This commit is contained in:
Lynne 2019-03-06 11:01:01 +00:00
parent 731c775898
commit 1cc8eecd38
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GPG Key ID: A2FEA5F03F034464
1 changed files with 25 additions and 1 deletions
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26
libavcodec/apedec.c
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@ -24,6 +24,7 @@
#include "libavutil/avassert.h"
#include "libavutil/channel_layout.h"
#include "libavutil/crc.h"
#include "libavutil/opt.h"
#include "lossless_audiodsp.h"
#include "avcodec.h"
@ -147,7 +148,8 @@ typedef struct APEContext {
int fset; ///< which filter set to use (calculated from compression level)
int flags; ///< global decoder flags
uint32_t CRC; ///< frame CRC
uint32_t CRC; ///< signalled frame CRC
uint32_t CRC_state; ///< accumulated CRC
int frameflags; ///< frame flags
APEPredictor predictor; ///< predictor used for final reconstruction
@ -750,6 +752,7 @@ static int init_entropy_decoder(APEContext *ctx)
/* Read the frame flags if they exist */
ctx->frameflags = 0;
ctx->CRC_state = UINT32_MAX;
if ((ctx->fileversion > 3820) && (ctx->CRC & 0x80000000)) {
ctx->CRC &= ~0x80000000;
@ -1577,6 +1580,27 @@ static int ape_decode_frame(AVCodecContext *avctx, void *data,
s->samples -= blockstodecode;
if (avctx->err_recognition & AV_EF_CRCCHECK &&
s->fileversion >= 3900 && s->bps < 24) {
uint32_t crc = s->CRC_state;
const AVCRC *crc_tab = av_crc_get_table(AV_CRC_32_IEEE_LE);
for (i = 0; i < blockstodecode; i++) {
for (ch = 0; ch < s->channels; ch++) {
uint8_t *smp = frame->data[ch] + (i*(s->bps >> 3));
crc = av_crc(crc_tab, crc, smp, s->bps >> 3);
}
}
if (!s->samples && (~crc >> 1) ^ s->CRC) {
av_log(avctx, AV_LOG_ERROR, "CRC mismatch! Previously decoded "
"frames may have been affected as well.\n");
if (avctx->err_recognition & AV_EF_EXPLODE)
return AVERROR_INVALIDDATA;
}
s->CRC_state = crc;
}
*got_frame_ptr = 1;
return !s->samples ? avpkt->size : 0;