[FFmpeg-devel] [PATCH] avcodec/ffv1enc: further reduce stack usage

[Martin Storsjö]

On Mon, 24 Mar 2025, James Almer wrote:

> On 3/24/2025 10:50 PM, Michael Niedermayer wrote:
>> Hi
>> 
>> On Mon, Mar 24, 2025 at 07:20:50PM -0300, James Almer wrote:
>>> Continues from commit 702239bc500b, fixing FATE failures on MacOS.
>>> 
>>> Signed-off-by: James Almer <jamrial at gmail.com>
>>> ---
>>> Confirmed by Martin Storsjö. Float encoding untested.
>>>
>>>   libavcodec/ffv1.h    |  16 ++++
>>>   libavcodec/ffv1enc.c | 177 +++++++++++++++++--------------------------
>>>   2 files changed, 84 insertions(+), 109 deletions(-)
>>> 
>>> diff --git a/libavcodec/ffv1.h b/libavcodec/ffv1.h
>>> index 09118e0b7d..d1c239f138 100644
>>> --- a/libavcodec/ffv1.h
>>> +++ b/libavcodec/ffv1.h
>>> @@ -115,6 +115,22 @@ typedef struct FFV1SliceContext {
>>>           uint32_t val; //this is unneeded if you accept a dereference on 
>>> each access
>>>           uint16_t ndx;
>>>       } unit[4][65536];
>>> +    struct RemapEncoderState {
>>> +        int delta_stack[65536];     //We need to encode the run value 
>>> before the adjustments, this stores the adjustments until we know the 
>>> length of the run
>>> +        int16_t index_stack[65537]; //only needed with multiple segments
>>> +        uint8_t state[2][3][32];
>>> +        int mul[4096+1];
>>> +        RangeCoder rc;
>>> +        int lu;
>>> +        int run;
>>> +        int64_t last_val;
>>> +        int compact_index;
>>> +        int mul_count;
>>> +        int i;
>>> +        int pixel_num;
>>> +        int p;
>>> +        int current_mul_index;
>>> +    } remap_state;
>>>   } FFV1SliceContext;
>> 
>> please provide a link to the failure
>
> Martin will have to do that. I can't seem to find any FATE instance failing, 
> but he said it affected his OSX machines.

I set up a couple of macOS FATE instances now, both which show the 
failure: 
https://fate.ffmpeg.org/history.cgi?slot=aarch64-apple-darwin-macos11
https://fate.ffmpeg.org/history.cgi?slot=x86_64-apple-darwin-macos11

// Martin