[FFmpeg-devel] [PATCH 1/3] avformat/takdec: Don't initialize get_bits context to read one value

[FFmpeg-devel] [PATCH 1/3] avformat/takdec: Don't initialize get_bits context to read one value

[Andreas Rheinhardt]

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/tak.h     | 1 -
 libavformat/takdec.c | 3 +--
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/libavcodec/tak.h b/libavcodec/tak.h
index dc45a8c070..6069118971 100644
--- a/libavcodec/tak.h
+++ b/libavcodec/tak.h
@@ -44,7 +44,6 @@
 #define TAK_LAST_FRAME_SIZE_BITS               24
 #define TAK_ENCODER_CODEC_BITS                  6
 #define TAK_ENCODER_PROFILE_BITS                4
-#define TAK_ENCODER_VERSION_BITS               24
 #define TAK_SAMPLE_RATE_MIN                  6000
 #define TAK_CHANNELS_MIN                        1
 #define TAK_BPS_MIN                             8
diff --git a/libavformat/takdec.c b/libavformat/takdec.c
index bb256e1190..cc1f049512 100644
--- a/libavformat/takdec.c
+++ b/libavformat/takdec.c
@@ -171,9 +171,8 @@ static int tak_read_header(AVFormatContext *s)
                               get_bits(&gb, TAK_LAST_FRAME_SIZE_BITS);
             av_freep(&buffer);
         } else if (type == TAK_METADATA_ENCODER) {
-            init_get_bits8(&gb, buffer, size - 3);
             av_log(s, AV_LOG_VERBOSE, "encoder version: %0X\n",
-                   get_bits_long(&gb, TAK_ENCODER_VERSION_BITS));
+                   AV_RL24(buffer));
             av_freep(&buffer);
         }
     }
-- 
2.32.0

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[FFmpeg-devel] [PATCH 2/3] avcodec/mlpdec: Use get_bits() instead of get_bits_long() when possible

[Andreas Rheinhardt]

huff_lsbs is guaranteed to be in the range of 0..24 and
so is lsb_bits here, so one can use get_bits().

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/mlpdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/mlpdec.c b/libavcodec/mlpdec.c
index 29fac54542..61b9a641dd 100644
--- a/libavcodec/mlpdec.c
+++ b/libavcodec/mlpdec.c
@@ -268,7 +268,7 @@ static inline int read_huff_channels(MLPDecodeContext *m, GetBitContext *gbp,
             return AVERROR_INVALIDDATA;
 
         if (lsb_bits > 0)
-            result = (result << lsb_bits) + get_bits_long(gbp, lsb_bits);
+            result = (result << lsb_bits) + get_bits(gbp, lsb_bits);
 
         result  += cp->sign_huff_offset;
         result *= 1 << quant_step_size;
-- 
2.32.0

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[FFmpeg-devel] [PATCH 3/3] avcodec/jpeglsdec: Avoid get_bits_long() where possible

[Andreas Rheinhardt]

It is possible here, because the values of ff_log2_run used
here are actually in the range 0..15 given that run_index is
in the range 0..31.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/jpeglsdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/jpeglsdec.c b/libavcodec/jpeglsdec.c
index 32c0d2eb3f..269c71dc18 100644
--- a/libavcodec/jpeglsdec.c
+++ b/libavcodec/jpeglsdec.c
@@ -277,7 +277,7 @@ static inline int ls_decode_line(JLSState *state, MJpegDecodeContext *s,
             /* decode aborted run */
             r = ff_log2_run[state->run_index[comp]];
             if (r)
-                r = get_bits_long(&s->gb, r);
+                r = get_bits(&s->gb, r);
             if (x + r * stride > w) {
                 r = (w - x) / stride;
             }
-- 
2.32.0

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Re: [FFmpeg-devel] [PATCH 2/3] avcodec/mlpdec: Use get_bits() instead of get_bits_long() when possible

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 1341 bytes --]

On Wed, Jan 05, 2022 at 10:38:34PM +0100, Andreas Rheinhardt wrote:
> huff_lsbs is guaranteed to be in the range of 0..24 and
> so is lsb_bits here, so one can use get_bits().
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
>  libavcodec/mlpdec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/mlpdec.c b/libavcodec/mlpdec.c
> index 29fac54542..61b9a641dd 100644
> --- a/libavcodec/mlpdec.c
> +++ b/libavcodec/mlpdec.c
> @@ -268,7 +268,7 @@ static inline int read_huff_channels(MLPDecodeContext *m, GetBitContext *gbp,
>              return AVERROR_INVALIDDATA;
>  
>          if (lsb_bits > 0)
> -            result = (result << lsb_bits) + get_bits_long(gbp, lsb_bits);
> +            result = (result << lsb_bits) + get_bits(gbp, lsb_bits);
>  
>          result  += cp->sign_huff_offset;
>          result *= 1 << quant_step_size;

This seems not to fully work

Assertion n>0 && n<=25 failed at libavcodec/get_bits.h:403

lsb_bits and cp->huff_lsbs are 31 in this failure, it seems
the checks that prevent this are conditional but i didnt debug/check this
any further

thx

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

Observe your enemies, for they first find out your faults. -- Antisthenes

[-- Attachment #1.2: signature.asc --]
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Re: [FFmpeg-devel] [PATCH 2/3] avcodec/mlpdec: Use get_bits() instead of get_bits_long() when possible

[Andreas Rheinhardt]

Michael Niedermayer:
> On Wed, Jan 05, 2022 at 10:38:34PM +0100, Andreas Rheinhardt wrote:
>> huff_lsbs is guaranteed to be in the range of 0..24 and
>> so is lsb_bits here, so one can use get_bits().
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
>> ---
>>  libavcodec/mlpdec.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavcodec/mlpdec.c b/libavcodec/mlpdec.c
>> index 29fac54542..61b9a641dd 100644
>> --- a/libavcodec/mlpdec.c
>> +++ b/libavcodec/mlpdec.c
>> @@ -268,7 +268,7 @@ static inline int read_huff_channels(MLPDecodeContext *m, GetBitContext *gbp,
>>              return AVERROR_INVALIDDATA;
>>  
>>          if (lsb_bits > 0)
>> -            result = (result << lsb_bits) + get_bits_long(gbp, lsb_bits);
>> +            result = (result << lsb_bits) + get_bits(gbp, lsb_bits);
>>  
>>          result  += cp->sign_huff_offset;
>>          result *= 1 << quant_step_size;
> 
> This seems not to fully work
> 
> Assertion n>0 && n<=25 failed at libavcodec/get_bits.h:403
> 
> lsb_bits and cp->huff_lsbs are 31 in this failure, it seems
> the checks that prevent this are conditional but i didnt debug/check this
> any further
> 

Seems like I misread the check at line 841: It does not apply to the
first codebook: if (cp->codebook > 0 && cp->huff_lsbs > 24) {
Thanks for testing, patch dropped.

- Andreas
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Re: [FFmpeg-devel] [PATCH 1/3] avformat/takdec: Don't initialize get_bits context to read one value

[Paul B Mahol]

LGTM
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Re: [FFmpeg-devel] [PATCH 3/3] avcodec/jpeglsdec: Avoid get_bits_long() where possible

[Andreas Rheinhardt]

Andreas Rheinhardt:
> It is possible here, because the values of ff_log2_run used
> here are actually in the range 0..15 given that run_index is
> in the range 0..31.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
>  libavcodec/jpeglsdec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/jpeglsdec.c b/libavcodec/jpeglsdec.c
> index 32c0d2eb3f..269c71dc18 100644
> --- a/libavcodec/jpeglsdec.c
> +++ b/libavcodec/jpeglsdec.c
> @@ -277,7 +277,7 @@ static inline int ls_decode_line(JLSState *state, MJpegDecodeContext *s,
>              /* decode aborted run */
>              r = ff_log2_run[state->run_index[comp]];
>              if (r)
> -                r = get_bits_long(&s->gb, r);
> +                r = get_bits(&s->gb, r);
>              if (x + r * stride > w) {
>                  r = (w - x) / stride;
>              }
> 

Will apply this patch tonight unless there are objections.

- Andreas
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