[FFmpeg-devel] [PATCH] avutil/hash: add 16-bit CRC type CCITT_AUG

[FFmpeg-devel] [PATCH] avutil/hash: add 16-bit CRC type CCITT_AUG

[Nuo Mi]

It is also referred to as:
    SPI-FUJITSU
    AUG-CCITT
    CRC-CCITT (0x1D0F)
This CRC type used by H.274
---
 libavutil/hash.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/libavutil/hash.c b/libavutil/hash.c
index fbc24194de..3659c71c7f 100644
--- a/libavutil/hash.c
+++ b/libavutil/hash.c
@@ -55,6 +55,7 @@
     ENTRY(SHA384,     "SHA384",     48) \
     ENTRY(SHA512,     "SHA512",     64) \
     ENTRY(CRC32,      "CRC32",       4) \
+    ENTRY(CCITT_AUG,  "CCITT_AUG",   2) \
     ENTRY(ADLER32,    "adler32",     4) \
 
 enum hashtype {
@@ -138,9 +139,10 @@ int av_hash_alloc(AVHashContext **ctx, const char *name)
     case SHA384:
     case SHA512:  res->ctx = av_sha512_alloc(); break;
     case CRC32:   res->crctab = av_crc_get_table(AV_CRC_32_IEEE_LE); break;
+    case CCITT_AUG:    res->crctab = av_crc_get_table(AV_CRC_16_CCITT); break;
     case ADLER32: break;
     }
-    if (i != ADLER32 && i != CRC32 && !res->ctx) {
+    if (i != ADLER32 && i != CRC32 && i != CCITT_AUG && !res->ctx) {
         av_free(res);
         return AVERROR(ENOMEM);
     }
@@ -165,6 +167,7 @@ void av_hash_init(AVHashContext *ctx)
     case SHA384:  av_sha512_init(ctx->ctx, 384); break;
     case SHA512:  av_sha512_init(ctx->ctx, 512); break;
     case CRC32:   ctx->crc = UINT32_MAX; break;
+    case CCITT_AUG:   ctx->crc = 0x0F1D; break; //Byte swapped value of 0x1D0F
     case ADLER32: ctx->crc = 1; break;
     }
 }
@@ -185,7 +188,8 @@ void av_hash_update(AVHashContext *ctx, const uint8_t *src, size_t len)
     case SHA512_256:
     case SHA384:
     case SHA512:  av_sha512_update(ctx->ctx, src, len); break;
-    case CRC32:   ctx->crc = av_crc(ctx->crctab, ctx->crc, src, len); break;
+    case CRC32:
+    case CCITT_AUG: ctx->crc = av_crc(ctx->crctab, ctx->crc, src, len); break;
     case ADLER32: ctx->crc = av_adler32_update(ctx->crc, src, len); break;
     }
 }
@@ -207,6 +211,7 @@ void av_hash_final(AVHashContext *ctx, uint8_t *dst)
     case SHA384:
     case SHA512:  av_sha512_final(ctx->ctx, dst); break;
     case CRC32:   AV_WB32(dst, ctx->crc ^ UINT32_MAX); break;
+    case CCITT_AUG: AV_WB16(dst, ctx->crc); break;
     case ADLER32: AV_WB32(dst, ctx->crc); break;
     }
 }
-- 
2.34.1

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Re: [FFmpeg-devel] [PATCH] avutil/hash: add 16-bit CRC type CCITT_AUG

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 586 bytes --]

Hi

On Tue, Mar 25, 2025 at 10:59:28PM +0800, Nuo Mi wrote:
> It is also referred to as:
>     SPI-FUJITSU
>     AUG-CCITT
>     CRC-CCITT (0x1D0F)
> This CRC type used by H.274
> ---
>  libavutil/hash.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

needs update to fate-hash

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many things microsoft did are stupid, but not doing something just because
microsoft did it is even more stupid. If everything ms did were stupid they
would be bankrupt already.

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]

[-- Attachment #2: Type: text/plain, Size: 251 bytes --]

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Re: [FFmpeg-devel] [PATCH] avutil/hash: add 16-bit CRC type CCITT_AUG

[Nuo Mi]

On Sat, Mar 29, 2025 at 6:21 AM Michael Niedermayer <michael@niedermayer.cc>
wrote:

> Hi
>
> On Tue, Mar 25, 2025 at 10:59:28PM +0800, Nuo Mi wrote:
> > It is also referred to as:
> >     SPI-FUJITSU
> >     AUG-CCITT
> >     CRC-CCITT (0x1D0F)
> > This CRC type used by H.274
> > ---
> >  libavutil/hash.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
>
> needs update to fate-hash
>
Hi Micheal,
Thank you for the review.
Reimar believes that the hash API may not be necessary
<https://github.com/ffvvc/FFmpeg/pull/283#issuecomment-2755799110> for h274.

We are still working on this and discussing the approach.
If we determine that the patch is still needed, I will update the fate-hash
accordingly.

>
> thx
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Many things microsoft did are stupid, but not doing something just because
> microsoft did it is even more stupid. If everything ms did were stupid they
> would be bankrupt already.
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>
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