[FFmpeg-devel] [PATCH V3 2/6] lavfi: use common VPP infrastructure for vf_scale_vaapi.

[Mark Thompson]

On 19/01/18 00:41, Jun Zhao wrote:
> On 2018/1/19 8:25, Mark Thompson wrote:
>> On 18/01/18 05:18, Jun Zhao wrote:
>>> From d157fdbffebd07066b1a857398e1067615f908b3 Mon Sep 17 00:00:00 2001
>>> From: Jun Zhao <jun.zhao at intel.com>
>>> Date: Mon, 8 Jan 2018 16:02:35 +0800
>>> Subject: [PATCH V3 2/6] lavfi: use common VPP infrastructure for
>>>  vf_scale_vaapi.
>>>
>>> Use the common VPP infrastructure re-work vf_scale_vaapi.
>>>
>>> Signed-off-by: Jun Zhao <jun.zhao at intel.com>
>>> ---
>>>  libavfilter/Makefile         |   2 +-
>>>  libavfilter/vf_scale_vaapi.c | 353 +++++--------------------------------------
>>>  2 files changed, 41 insertions(+), 314 deletions(-)
>>>
>>> ...
>>>  
>>>  static av_cold int scale_vaapi_init(AVFilterContext *avctx)
>>>  {
>>> -    ScaleVAAPIContext *ctx = avctx->priv;
>>> +    VAAPIVPPContext *vpp_ctx = avctx->priv;
>>> +    ScaleVAAPIContext *ctx   = (ScaleVAAPIContext *)vpp_ctx->priv_data;
>> The extra indirection means this is reading ctx before it's set.  E.g. try:
>>
>> $ gdb --args ./ffmpeg_g -y -hwaccel vaapi -hwaccel_device /dev/dri/renderD129 -hwaccel_output_format vaapi -i input.mp4 -vf 'scale_vaapi=format=invalid' -f null -
>> ...
>> Thread 1 "ffmpeg_g" received signal SIGSEGV, Segmentation fault.
>> 0x0000555556927515 in format_line (avcl=0x55555843b950, level=16, fmt=0x555556984f69 "Invalid output format.\n", vl=0x7fffffffcfb0, part=0x7fffffffbf20, print_prefix=0x55555708c708 <print_prefix>, type=0x7fffffffbb18) at src/libavutil/log.c:258
>> 258                 AVClass** parent = *(AVClass ***) (((uint8_t *) avcl) +
>> (gdb) bt
>> #0  0x0000555556927515 in format_line (avcl=0x55555843b950, level=16, fmt=0x555556984f69 "Invalid output format.\n", vl=0x7fffffffcfb0, part=0x7fffffffbf20, print_prefix=0x55555708c708 <print_prefix>, type=0x7fffffffbb18) at src/libavutil/log.c:258
>> #1  0x00005555569278da in av_log_default_callback (ptr=0x55555843b950, level=16, fmt=0x555556984f69 "Invalid output format.\n", vl=0x7fffffffcfb0) at src/libavutil/log.c:320
>> #2  0x0000555556927d05 in av_vlog (avcl=0x55555843b950, level=16, fmt=0x555556984f69 "Invalid output format.\n", vl=0x7fffffffcfb0) at src/libavutil/log.c:377
>> #3  0x0000555556927cc4 in av_log (avcl=0x55555843b950, level=16, fmt=0x555556984f69 "Invalid output format.\n") at src/libavutil/log.c:369
>> #4  0x0000555555844bac in scale_vaapi_init (avctx=0x55555836ad80) at src/libavfilter/vf_scale_vaapi.c:151
>>
>>
>> I still think having VAAPIVPPContext as the first element of ScaleVAAPIContext would be cleaner.
>>
> This issue have been fix in local, if we put VAAPIVPPContext as the
> first element of ScaleVAAPIContex, I can't find a way to reuse VPP
> common APP.
> 
> e,g, for: scale_vaapi_vpp_config_input, need to implement as: (the first
> version )
> 
>  
>  static int scale_vaapi_config_input(AVFilterLink *inlink)
>  {
>      AVFilterContext *avctx = inlink->dst;
>      ScaleVAAPIContext *ctx = avctx->priv;
> VAAPIVPPContext *vpp_ctx = ctx->vpp_ctx;  return vaapi_vpp_config_input(inlink, vpp_ctx);
>  } 

No, you don't need this function - it's completely equivalent to calling ff_vaapi_vpp_context_input() directly in what you currently have, because avctx->priv is a pointer to both the ScaleVAAPIContext and its first member which is the VAAPIVPPContext.

- Mark