* [FFmpeg-devel] [PATCH] lavc/vvc: Correct sps_num_subpics_minus1 minimum
@ 2024-02-25 17:51 Frank Plowman
2024-02-25 19:50 ` James Almer
0 siblings, 1 reply; 4+ messages in thread
From: Frank Plowman @ 2024-02-25 17:51 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Frank Plowman
The spec says "the value of sps_num_subpics_minus1 shall be in the
range of 0 to MaxSlicesPerAu − 1, inclusive."
Signed-off-by: Frank Plowman <post@frankplowman.com>
---
libavcodec/cbs_h266_syntax_template.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libavcodec/cbs_h266_syntax_template.c b/libavcodec/cbs_h266_syntax_template.c
index 26ee7a420b..1d4d0c796f 100644
--- a/libavcodec/cbs_h266_syntax_template.c
+++ b/libavcodec/cbs_h266_syntax_template.c
@@ -1130,7 +1130,7 @@ static int FUNC(sps)(CodedBitstreamContext *ctx, RWContext *rw,
flag(sps_subpic_info_present_flag);
if (current->sps_subpic_info_present_flag) {
- ue(sps_num_subpics_minus1, 1, VVC_MAX_SLICES - 1);
+ ue(sps_num_subpics_minus1, 0, VVC_MAX_SLICES - 1);
if (current->sps_num_subpics_minus1 > 0) {
flag(sps_independent_subpics_flag);
flag(sps_subpic_same_size_flag);
--
2.43.2
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [FFmpeg-devel] [PATCH] lavc/vvc: Correct sps_num_subpics_minus1 minimum
2024-02-25 17:51 [FFmpeg-devel] [PATCH] lavc/vvc: Correct sps_num_subpics_minus1 minimum Frank Plowman
@ 2024-02-25 19:50 ` James Almer
2024-02-25 21:20 ` Frank Plowman
0 siblings, 1 reply; 4+ messages in thread
From: James Almer @ 2024-02-25 19:50 UTC (permalink / raw)
To: ffmpeg-devel
On 2/25/2024 2:51 PM, Frank Plowman wrote:
> The spec says "the value of sps_num_subpics_minus1 shall be in the
> range of 0 to MaxSlicesPerAu − 1, inclusive."
>
> Signed-off-by: Frank Plowman <post@frankplowman.com>
> ---
> libavcodec/cbs_h266_syntax_template.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/cbs_h266_syntax_template.c b/libavcodec/cbs_h266_syntax_template.c
> index 26ee7a420b..1d4d0c796f 100644
> --- a/libavcodec/cbs_h266_syntax_template.c
> +++ b/libavcodec/cbs_h266_syntax_template.c
> @@ -1130,7 +1130,7 @@ static int FUNC(sps)(CodedBitstreamContext *ctx, RWContext *rw,
>
> flag(sps_subpic_info_present_flag);
> if (current->sps_subpic_info_present_flag) {
> - ue(sps_num_subpics_minus1, 1, VVC_MAX_SLICES - 1);
> + ue(sps_num_subpics_minus1, 0, VVC_MAX_SLICES - 1);
Strictly speaking, MaxSlicesPerAu varies depending on the stream's
general_level_idc value, listed in table A.2 from Annex-A (in ITU-T
H.266 V3).
Right now, VVC_MAX_SLICES is defined as 600 in vvc.h, but the max value
in the spec is 1000, from level 6.3. I assume it was added in V3?
> if (current->sps_num_subpics_minus1 > 0) {
> flag(sps_independent_subpics_flag);
> flag(sps_subpic_same_size_flag);
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [FFmpeg-devel] [PATCH] lavc/vvc: Correct sps_num_subpics_minus1 minimum
2024-02-25 19:50 ` James Almer
@ 2024-02-25 21:20 ` Frank Plowman
2024-02-27 6:08 ` Nuo Mi
0 siblings, 1 reply; 4+ messages in thread
From: Frank Plowman @ 2024-02-25 21:20 UTC (permalink / raw)
To: ffmpeg-devel
On 25/02/2024 19:50, James Almer wrote:
> On 2/25/2024 2:51 PM, Frank Plowman wrote:
>> The spec says "the value of sps_num_subpics_minus1 shall be in the
>> range of 0 to MaxSlicesPerAu − 1, inclusive."
>>
>> Signed-off-by: Frank Plowman <post@frankplowman.com>
>> ---
>> libavcodec/cbs_h266_syntax_template.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavcodec/cbs_h266_syntax_template.c
>> b/libavcodec/cbs_h266_syntax_template.c
>> index 26ee7a420b..1d4d0c796f 100644
>> --- a/libavcodec/cbs_h266_syntax_template.c
>> +++ b/libavcodec/cbs_h266_syntax_template.c
>> @@ -1130,7 +1130,7 @@ static int FUNC(sps)(CodedBitstreamContext *ctx,
>> RWContext *rw,
>> flag(sps_subpic_info_present_flag);
>> if (current->sps_subpic_info_present_flag) {
>> - ue(sps_num_subpics_minus1, 1, VVC_MAX_SLICES - 1);
>> + ue(sps_num_subpics_minus1, 0, VVC_MAX_SLICES - 1);
>
> Strictly speaking, MaxSlicesPerAu varies depending on the stream's
> general_level_idc value, listed in table A.2 from Annex-A (in ITU-T
> H.266 V3).
>
> Right now, VVC_MAX_SLICES is defined as 600 in vvc.h, but the max value
> in the spec is 1000, from level 6.3. I assume it was added in V3?
Good catch. It looks like level 6.3 has been in the spec since the
first version, but all the VVC_MAX_* definitions derived from Annex A
did not account for it. Here is a patch which corrects this:
https://ffmpeg.org//pipermail/ffmpeg-devel/2024-February/322140.html
>> if (current->sps_num_subpics_minus1 > 0) {
>> flag(sps_independent_subpics_flag);
>> flag(sps_subpic_same_size_flag);
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [FFmpeg-devel] [PATCH] lavc/vvc: Correct sps_num_subpics_minus1 minimum
2024-02-25 21:20 ` Frank Plowman
@ 2024-02-27 6:08 ` Nuo Mi
0 siblings, 0 replies; 4+ messages in thread
From: Nuo Mi @ 2024-02-27 6:08 UTC (permalink / raw)
To: FFmpeg development discussions and patches
On Mon, Feb 26, 2024 at 5:20 AM Frank Plowman <post@frankplowman.com> wrote:
> On 25/02/2024 19:50, James Almer wrote:
> > On 2/25/2024 2:51 PM, Frank Plowman wrote:
> >> The spec says "the value of sps_num_subpics_minus1 shall be in the
> >> range of 0 to MaxSlicesPerAu − 1, inclusive."
> >>
> >> Signed-off-by: Frank Plowman <post@frankplowman.com>
> >> ---
> >> libavcodec/cbs_h266_syntax_template.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/libavcodec/cbs_h266_syntax_template.c
> >> b/libavcodec/cbs_h266_syntax_template.c
> >> index 26ee7a420b..1d4d0c796f 100644
> >> --- a/libavcodec/cbs_h266_syntax_template.c
> >> +++ b/libavcodec/cbs_h266_syntax_template.c
> >> @@ -1130,7 +1130,7 @@ static int FUNC(sps)(CodedBitstreamContext *ctx,
> >> RWContext *rw,
> >> flag(sps_subpic_info_present_flag);
> >> if (current->sps_subpic_info_present_flag) {
> >> - ue(sps_num_subpics_minus1, 1, VVC_MAX_SLICES - 1);
> >> + ue(sps_num_subpics_minus1, 0, VVC_MAX_SLICES - 1);
> >
> > Strictly speaking, MaxSlicesPerAu varies depending on the stream's
> > general_level_idc value, listed in table A.2 from Annex-A (in ITU-T
> > H.266 V3).
> >
> > Right now, VVC_MAX_SLICES is defined as 600 in vvc.h, but the max value
> > in the spec is 1000, from level 6.3. I assume it was added in V3?
>
> Good catch. It looks like level 6.3 has been in the spec since the
> first version, but all the VVC_MAX_* definitions derived from Annex A
> did not account for it. Here is a patch which corrects this:
> https://ffmpeg.org//pipermail/ffmpeg-devel/2024-February/322140.html
No, level 6.3 was not present in v1 (08/2020); it was added in v2 (04/2022).
>
> >> if (current->sps_num_subpics_minus1 > 0) {
> >> flag(sps_independent_subpics_flag);
> >> flag(sps_subpic_same_size_flag);
> _______________________________________________
> 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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^ permalink raw reply [flat|nested] 4+ messages in thread
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2024-02-25 17:51 [FFmpeg-devel] [PATCH] lavc/vvc: Correct sps_num_subpics_minus1 minimum Frank Plowman
2024-02-25 19:50 ` James Almer
2024-02-25 21:20 ` Frank Plowman
2024-02-27 6:08 ` Nuo Mi
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