[FFmpeg-devel] [PATCH] avformat/mov: ensure pasp box derived SAR is used if present

[FFmpeg-devel] [PATCH] avformat/mov: ensure pasp box derived SAR is used if present

[James Almer]

It's meant to override any codec specific (but container level) information,
but its position is not guaranteed, so apply the values after the entire trak
structure has been parsed.
Also, replace the ugly roundabout int -> double -> int method to set SAR from
existing dimensions while at it.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavformat/isom.h |  2 ++
 libavformat/mov.c  | 16 ++++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/libavformat/isom.h b/libavformat/isom.h
index a0498f45e5..5b6125a908 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -215,6 +215,8 @@ typedef struct MOVStreamContext {
     int timecode_track;
     int width;            ///< tkhd width
     int height;           ///< tkhd height
+    int h_spacing;        ///< pasp hSpacing
+    int v_spacing;        ///< pasp vSpacing
     int dts_shift;        ///< dts shift when ctts is negative
     uint32_t palette[256];
     int has_palette;
diff --git a/libavformat/mov.c b/libavformat/mov.c
index ced4b2e6b3..ce95842ce5 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1287,14 +1287,18 @@ static int mov_read_pasp(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     const int num = avio_rb32(pb);
     const int den = avio_rb32(pb);
     AVStream *st;
+    MOVStreamContext *sc;
 
     if (c->fc->nb_streams < 1)
         return 0;
     st = c->fc->streams[c->fc->nb_streams-1];
+    sc = st->priv_data;
+
+    av_log(c->fc, AV_LOG_TRACE, "pasp: hSpacing %d, vSpacing %d\n", num, den);
 
     if (den != 0) {
-        av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
-                  num, den, 32767);
+        sc->h_spacing = num;
+        sc->v_spacing = den;
     }
     return 0;
 }
@@ -5031,11 +5035,15 @@ static int mov_read_trak(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     }
 
     if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
+        if (sc->h_spacing && sc->v_spacing)
+            av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
+                      sc->h_spacing, sc->v_spacing, INT_MAX);
         if (!st->sample_aspect_ratio.num && st->codecpar->width && st->codecpar->height &&
             sc->height && sc->width &&
             (st->codecpar->width != sc->width || st->codecpar->height != sc->height)) {
-            st->sample_aspect_ratio = av_d2q(((double)st->codecpar->height * sc->width) /
-                                             ((double)st->codecpar->width * sc->height), INT_MAX);
+            av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
+                      (int64_t)st->codecpar->height * sc->width,
+                      (int64_t)st->codecpar->width  * sc->height, INT_MAX);
         }
 
 #if FF_API_R_FRAME_RATE
-- 
2.45.2

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Re: [FFmpeg-devel] [PATCH] avformat/mov: ensure pasp box derived SAR is used if present

[Leo Izen]

On 7/9/24 1:21 PM, James Almer wrote:
> It's meant to override any codec specific (but container level) information,
> but its position is not guaranteed, so apply the values after the entire trak
> structure has been parsed.
> Also, replace the ugly roundabout int -> double -> int method to set SAR from
> existing dimensions while at it.
> 
> Signed-off-by: James Almer <jamrial@gmail.com>
> ---
>   libavformat/isom.h |  2 ++
>   libavformat/mov.c  | 16 ++++++++++++----
>   2 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/libavformat/isom.h b/libavformat/isom.h
> index a0498f45e5..5b6125a908 100644
> --- a/libavformat/isom.h
> +++ b/libavformat/isom.h
> @@ -215,6 +215,8 @@ typedef struct MOVStreamContext {
>       int timecode_track;
>       int width;            ///< tkhd width
>       int height;           ///< tkhd height
> +    int h_spacing;        ///< pasp hSpacing
> +    int v_spacing;        ///< pasp vSpacing
>       int dts_shift;        ///< dts shift when ctts is negative
>       uint32_t palette[256];
>       int has_palette;
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index ced4b2e6b3..ce95842ce5 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -1287,14 +1287,18 @@ static int mov_read_pasp(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>       const int num = avio_rb32(pb);
>       const int den = avio_rb32(pb);
>       AVStream *st;
> +    MOVStreamContext *sc;
>   
>       if (c->fc->nb_streams < 1)
>           return 0;
>       st = c->fc->streams[c->fc->nb_streams-1];
> +    sc = st->priv_data;
> +
> +    av_log(c->fc, AV_LOG_TRACE, "pasp: hSpacing %d, vSpacing %d\n", num, den);
>   
>       if (den != 0) {
> -        av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
> -                  num, den, 32767);
> +        sc->h_spacing = num;
> +        sc->v_spacing = den;
>       }

If den == 0, nothing is assigned at all, but if den != 0 and if num == 
0, we assign 0 to h_spacing, which will end up doing nothing because we 
check h_spacing && v_spacing later on in the other line you add.

Is this intentional? Is this desired behavior? etc.

- Leo Izen (Traneptora)

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Re: [FFmpeg-devel] [PATCH] avformat/mov: ensure pasp box derived SAR is used if present

[James Almer]

On 7/10/2024 1:02 PM, Leo Izen wrote:
> On 7/9/24 1:21 PM, James Almer wrote:
>> It's meant to override any codec specific (but container level) 
>> information,
>> but its position is not guaranteed, so apply the values after the 
>> entire trak
>> structure has been parsed.
>> Also, replace the ugly roundabout int -> double -> int method to set 
>> SAR from
>> existing dimensions while at it.
>>
>> Signed-off-by: James Almer <jamrial@gmail.com>
>> ---
>>   libavformat/isom.h |  2 ++
>>   libavformat/mov.c  | 16 ++++++++++++----
>>   2 files changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/libavformat/isom.h b/libavformat/isom.h
>> index a0498f45e5..5b6125a908 100644
>> --- a/libavformat/isom.h
>> +++ b/libavformat/isom.h
>> @@ -215,6 +215,8 @@ typedef struct MOVStreamContext {
>>       int timecode_track;
>>       int width;            ///< tkhd width
>>       int height;           ///< tkhd height
>> +    int h_spacing;        ///< pasp hSpacing
>> +    int v_spacing;        ///< pasp vSpacing
>>       int dts_shift;        ///< dts shift when ctts is negative
>>       uint32_t palette[256];
>>       int has_palette;
>> diff --git a/libavformat/mov.c b/libavformat/mov.c
>> index ced4b2e6b3..ce95842ce5 100644
>> --- a/libavformat/mov.c
>> +++ b/libavformat/mov.c
>> @@ -1287,14 +1287,18 @@ static int mov_read_pasp(MOVContext *c, 
>> AVIOContext *pb, MOVAtom atom)
>>       const int num = avio_rb32(pb);
>>       const int den = avio_rb32(pb);
>>       AVStream *st;
>> +    MOVStreamContext *sc;
>>       if (c->fc->nb_streams < 1)
>>           return 0;
>>       st = c->fc->streams[c->fc->nb_streams-1];
>> +    sc = st->priv_data;
>> +
>> +    av_log(c->fc, AV_LOG_TRACE, "pasp: hSpacing %d, vSpacing %d\n", 
>> num, den);
>>       if (den != 0) {
>> -        av_reduce(&st->sample_aspect_ratio.num, 
>> &st->sample_aspect_ratio.den,
>> -                  num, den, 32767);
>> +        sc->h_spacing = num;
>> +        sc->v_spacing = den;
>>       }
> 
> If den == 0, nothing is assigned at all, but if den != 0 and if num == 
> 0, we assign 0 to h_spacing, which will end up doing nothing because we 
> check h_spacing && v_spacing later on in the other line you add.
> 
> Is this intentional? Is this desired behavior? etc.

A 0/x SAR is just 0, or unset, regardless of the value for den, and we 
check for sar.num immediately after the "sc->h_spacing && sc->v_spacing" 
one and set it to something if it's 0, so it will make no difference.
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Re: [FFmpeg-devel] [PATCH] avformat/mov: ensure pasp box derived SAR is used if present

[James Almer]

On 7/9/2024 2:21 PM, James Almer wrote:
> It's meant to override any codec specific (but container level) information,
> but its position is not guaranteed, so apply the values after the entire trak
> structure has been parsed.
> Also, replace the ugly roundabout int -> double -> int method to set SAR from
> existing dimensions while at it.
> 
> Signed-off-by: James Almer <jamrial@gmail.com>
> ---
>   libavformat/isom.h |  2 ++
>   libavformat/mov.c  | 16 ++++++++++++----
>   2 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/libavformat/isom.h b/libavformat/isom.h
> index a0498f45e5..5b6125a908 100644
> --- a/libavformat/isom.h
> +++ b/libavformat/isom.h
> @@ -215,6 +215,8 @@ typedef struct MOVStreamContext {
>       int timecode_track;
>       int width;            ///< tkhd width
>       int height;           ///< tkhd height
> +    int h_spacing;        ///< pasp hSpacing
> +    int v_spacing;        ///< pasp vSpacing
>       int dts_shift;        ///< dts shift when ctts is negative
>       uint32_t palette[256];
>       int has_palette;
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index ced4b2e6b3..ce95842ce5 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -1287,14 +1287,18 @@ static int mov_read_pasp(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>       const int num = avio_rb32(pb);
>       const int den = avio_rb32(pb);
>       AVStream *st;
> +    MOVStreamContext *sc;
>   
>       if (c->fc->nb_streams < 1)
>           return 0;
>       st = c->fc->streams[c->fc->nb_streams-1];
> +    sc = st->priv_data;
> +
> +    av_log(c->fc, AV_LOG_TRACE, "pasp: hSpacing %d, vSpacing %d\n", num, den);
>   
>       if (den != 0) {
> -        av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
> -                  num, den, 32767);
> +        sc->h_spacing = num;
> +        sc->v_spacing = den;
>       }
>       return 0;
>   }
> @@ -5031,11 +5035,15 @@ static int mov_read_trak(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>       }
>   
>       if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
> +        if (sc->h_spacing && sc->v_spacing)
> +            av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
> +                      sc->h_spacing, sc->v_spacing, INT_MAX);
>           if (!st->sample_aspect_ratio.num && st->codecpar->width && st->codecpar->height &&
>               sc->height && sc->width &&
>               (st->codecpar->width != sc->width || st->codecpar->height != sc->height)) {
> -            st->sample_aspect_ratio = av_d2q(((double)st->codecpar->height * sc->width) /
> -                                             ((double)st->codecpar->width * sc->height), INT_MAX);
> +            av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
> +                      (int64_t)st->codecpar->height * sc->width,
> +                      (int64_t)st->codecpar->width  * sc->height, INT_MAX);
>           }
>   
>   #if FF_API_R_FRAME_RATE

Will apply.
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