A lot of files have CRC included.
The CRC only covers 34 bytes at most from the frame but it should still be
enough for some amount of error detection.
>From e1f4410f35d3d7f774a0de59ab72764033d14900 Mon Sep 17 00:00:00 2001
From: Lynne <[email protected]>
Date: Wed, 6 Mar 2019 17:04:04 +0000
Subject: [PATCH] mpegaudiodec_template: add ability to check CRC
A lot of files have CRC included.
The CRC only covers 34 bytes at most from the frame but it should still be
enough for some amount of error detection.
---
libavcodec/mpegaudiodec_template.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/libavcodec/mpegaudiodec_template.c b/libavcodec/mpegaudiodec_template.c
index 9cce88e263..0881b60bf5 100644
--- a/libavcodec/mpegaudiodec_template.c
+++ b/libavcodec/mpegaudiodec_template.c
@@ -27,6 +27,7 @@
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/channel_layout.h"
+#include "libavutil/crc.h"
#include "libavutil/float_dsp.h"
#include "libavutil/libm.h"
#include "avcodec.h"
@@ -1565,9 +1566,22 @@ static int mp_decode_frame(MPADecodeContext *s, OUT_INT **samples,
init_get_bits(&s->gb, buf + HEADER_SIZE, (buf_size - HEADER_SIZE) * 8);
- /* skip error protection field */
- if (s->error_protection)
- skip_bits(&s->gb, 16);
+ if (s->error_protection) {
+ uint16_t crc = get_bits(&s->gb, 16);
+ if (s->err_recognition & AV_EF_CRCCHECK) {
+ const int sec_len = s->lsf ? ((s->nb_channels == 1) ? 9 : 17) :
+ ((s->nb_channels == 1) ? 17 : 32);
+ const AVCRC *crc_tab = av_crc_get_table(AV_CRC_16_ANSI);
+ uint32_t crc_cal = av_crc(crc_tab, UINT16_MAX, &buf[2], 2);
+ crc_cal = av_crc(crc_tab, crc_cal, &buf[6], sec_len);
+
+ if (av_bswap16(crc) ^ crc_cal) {
+ av_log(s->avctx, AV_LOG_ERROR, "CRC mismatch!\n");
+ if (s->err_recognition & AV_EF_EXPLODE)
+ return AVERROR_INVALIDDATA;
+ }
+ }
+ }
switch(s->layer) {
case 1:
--
2.21.0
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