[FFmpeg-devel] [PATCH v2 1/1] avfilter/frames: Ensure frames are writable when processing in-place

[James Almer]

On 9/28/2021 6:00 PM, Soft Works wrote:
> 
> 
>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
>> James Almer
>> Sent: Tuesday, 28 September 2021 22:08
>> To: ffmpeg-devel at ffmpeg.org
>> Subject: Re: [FFmpeg-devel] [PATCH v2 1/1] avfilter/frames: Ensure
>> frames are writable when processing in-place
>>
>> On 9/28/2021 4:54 PM, Soft Works wrote:
>>> Signed-off-by: softworkz <softworkz at hotmail.com>
>>> ---
>>> v2: Reduced to cases without AVFILTERPAD_FLAG_NEEDS_WRITABLE
>>
>> Can't this flag used in these filters?
> 
> Not in vf_vflip, because in case of flip_bayer, it's using a
> custom allocation (.get_buffer.video)
> 
>>>    libavfilter/vf_cover_rect.c | 7 +++++--
>>>    libavfilter/vf_floodfill.c  | 5 +++++
>>>    libavfilter/vf_vflip.c      | 7 ++++++-
>>>    3 files changed, 16 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/libavfilter/vf_cover_rect.c
>> b/libavfilter/vf_cover_rect.c
>>> index 0a8c10e06d..2367afb4b3 100644
>>> --- a/libavfilter/vf_cover_rect.c
>>> +++ b/libavfilter/vf_cover_rect.c
>>> @@ -136,7 +136,7 @@ static int filter_frame(AVFilterLink *inlink,
>> AVFrame *in)
>>>        AVFilterContext *ctx = inlink->dst;
>>>        CoverContext *cover = ctx->priv;
>>>        AVDictionaryEntry *ex, *ey, *ew, *eh;
>>> -    int x = -1, y = -1, w = -1, h = -1;
>>> +    int x = -1, y = -1, w = -1, h = -1, ret;
>>>        char *xendptr = NULL, *yendptr = NULL, *wendptr = NULL,
>> *hendptr = NULL;
>>>
>>>        ex = av_dict_get(in->metadata, "lavfi.rect.x", NULL,
>> AV_DICT_MATCH_CASE);
>>> @@ -181,7 +181,10 @@ static int filter_frame(AVFilterLink *inlink,
>> AVFrame *in)
>>>        x = av_clip(x, 0, in->width  - w);
>>>        y = av_clip(y, 0, in->height - h);
>>>
>>> -    av_frame_make_writable(in);
>>> +    if ((ret = av_frame_make_writable(in)) < 0) {
>>> +        av_frame_free(&in);
>>> +        return ret;
>>> +    }
>>>
>>>        if (cover->mode == MODE_BLUR) {
>>>            blur (cover, in, x, y);
>>> diff --git a/libavfilter/vf_floodfill.c
>> b/libavfilter/vf_floodfill.c
>>> index 21741cdb4f..292b27505e 100644
>>> --- a/libavfilter/vf_floodfill.c
>>> +++ b/libavfilter/vf_floodfill.c
>>> @@ -294,6 +294,11 @@ static int filter_frame(AVFilterLink *link,
>> AVFrame *frame)
>>>        const int h = frame->height;
>>>        int i, ret;
>>>
>>> +    if ((ret = av_frame_make_writable(frame)) < 0) {
>>> +        av_frame_free(&frame);
>>> +        return ret;
>>> +    }
>>> +
>>>        if (is_inside(s->x, s->y, w, h)) {
>>>            s->pick_pixel(frame, s->x, s->y, &s0, &s1, &s2, &s3);
>>>
>>> diff --git a/libavfilter/vf_vflip.c b/libavfilter/vf_vflip.c
>>> index 0d624512f9..622bd46db3 100644
>>> --- a/libavfilter/vf_vflip.c
>>> +++ b/libavfilter/vf_vflip.c
>>> @@ -108,11 +108,16 @@ static int flip_bayer(AVFilterLink *link,
>> AVFrame *in)
>>>    static int filter_frame(AVFilterLink *link, AVFrame *frame)
>>>    {
>>>        FlipContext *flip = link->dst->priv;
>>> -    int i;
>>> +    int i, ret;
>>>
>>>        if (flip->bayer)
>>>            return flip_bayer(link, frame);
>>>
>>> +    if ((ret = av_frame_make_writable(frame)) < 0) {
>>
>> vf_vflip defines a custom get_buffer.video() function, so you can't
>> use
>> av_frame_make_writable() as the buffer it will return in case it
>> needs
>> to allocate a writable one may not be suitable. You need to use
>> ff_inlink_make_frame_writable() instead, and in all three filters
>> while
>> at it.
> 
> .get_buffer.video is used for the case of flip_bayer, but not otherwise.
> Otherwise it was currently writing to the incoming frame directly,
> and that's what this patch fixes.

Ok, but i insist you should use ff_inlink_make_frame_writable(). If it 
wont use the vflip custom get_buffer.video function, it will instead use 
the default allocator, which makes use of a lavfi frame pool.

> 
> softworkz
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