Re: [FFmpeg-devel] [PATCH] Add support for spherical uuid in mov

[Derek Buitenhuis]

On 4/21/2016 9:13 AM, Hendrik Leppkes wrote:
> One developer from Libav is working on defining side-data for this
> spherical data. If you want to push this forward I suggest you join
> those efforts.
> ie. this patch for mov: https://patches.libav.org/patch/60300/ (part
> of a longer series)

Yes, please. I would not like competing APIs, as a downstream user.

They are in IRC, as well.

- Derek
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Re: [FFmpeg-devel] [PATCH] Add support for spherical uuid in mov

[Hendrik Leppkes]

On Thu, Apr 21, 2016 at 10:10 AM, wm4  wrote:
> On Wed, 20 Apr 2016 19:46:05 -0700
> Neil Birkbeck  wrote:
>
>> If you use "spherical-video" and put it in the stream's metadata, it
>> will more naturally agree with location in stream-level tag in mkv:
>> https://github.com/google/spatial-media/blob/master/docs/spherical-video-rfc.md
>
> (Replying to both.)
>
> This kind of metadata is basically for user info and things like tags.
> It should NOT be used to export semantic/mandatory information about
> the video stream.
>
> To make it even worse, ffmpeg.c will happily put those tags into other
> container/codecs, which means using metadata for this information will
> likely produce broken files that can only be read by ffmpeg itself.

One developer from Libav is working on defining side-data for this
spherical data. If you want to push this forward I suggest you join
those efforts.
ie. this patch for mov: https://patches.libav.org/patch/60300/ (part
of a longer series)

- Hendrik
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Re: [FFmpeg-devel] [PATCH] Add support for spherical uuid in mov

[wm4]

On Wed, 20 Apr 2016 19:46:05 -0700
Neil Birkbeck  wrote:

> If you use "spherical-video" and put it in the stream's metadata, it
> will more naturally agree with location in stream-level tag in mkv:
> https://github.com/google/spatial-media/blob/master/docs/spherical-video-rfc.md

(Replying to both.)

This kind of metadata is basically for user info and things like tags.
It should NOT be used to export semantic/mandatory information about
the video stream.

To make it even worse, ffmpeg.c will happily put those tags into other
container/codecs, which means using metadata for this information will
likely produce broken files that can only be read by ffmpeg itself.
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Re: [FFmpeg-devel] [PATCH] Add support for spherical uuid in mov

[Colin McFadden]

That makes sense.  I’ve attached a revised patch which will store a 
“spherical-video” tag in stream metadata, assuming we have a stream (moov level 
uuid atoms shouldn’t have spherical metadata according to the RFC).

This is my first time submitting an ffmpeg patch, so please clue me in if I’m 
off the rails.  Thanks!

-Colin




0001-Add-support-for-spherical-metadata-from-uuid-atom-st.patch
Description: Binary data


> On Apr 20, 2016, at 9:46 PM, Neil Birkbeck  wrote:
> 
> If you use "spherical-video" and put it in the stream's metadata, it
> will more naturally agree with location in stream-level tag in mkv:
> https://github.com/google/spatial-media/blob/master/docs/spherical-video-rfc.md
> 
> On Wed, Apr 20, 2016 at 6:24 PM, Colin McFadden  wrote:
>> ---
>> libavformat/mov.c | 26 ++
>> 1 file changed, 26 insertions(+)
>> 
>> diff --git a/libavformat/mov.c b/libavformat/mov.c
>> index 47af98c..2223c81 100644
>> --- a/libavformat/mov.c
>> +++ b/libavformat/mov.c
>> @@ -3912,6 +3912,11 @@ static int mov_read_uuid(MOVContext *c, AVIOContext 
>> *pb, MOVAtom atom)
>> 0xbe, 0x7a, 0xcf, 0xcb, 0x97, 0xa9, 0x42, 0xe8,
>> 0x9c, 0x71, 0x99, 0x94, 0x91, 0xe3, 0xaf, 0xac
>> };
>> + static const uint8_t uuid_spherical[] = {
>> +0xFF, 0xCC, 0x82, 0x63, 0xF8, 0x55, 0x4A, 0x93,
>> +0x88, 0x14, 0x58, 0x7A, 0x02, 0x52, 0x1F, 0xDD
>> +};
>> +
>> 
>> if (atom.size < sizeof(uuid) || atom.size == INT64_MAX)
>> return AVERROR_INVALIDDATA;
>> @@ -3987,6 +3992,27 @@ static int mov_read_uuid(MOVContext *c, AVIOContext 
>> *pb, MOVAtom atom)
>> av_dict_set(>fc->metadata, "xmp", buffer, 0);
>> }
>> av_free(buffer);
>> +} else if (!memcmp(uuid, uuid_spherical, sizeof(uuid))) {
>> +uint8_t *buffer;
>> +size_t len = atom.size - sizeof(uuid);
>> +
>> +buffer = av_mallocz(len + 1);
>> +if (!buffer) {
>> +return AVERROR(ENOMEM);
>> +}
>> +ret = avio_read(pb, buffer, len);
>> +if (ret < 0) {
>> +av_free(buffer);
>> +return ret;
>> +} else if (ret != len) {
>> +av_free(buffer);
>> +return AVERROR_INVALIDDATA;
>> +}
>> +if (c->export_all) {
>> +buffer[len] = '\0';
>> +av_dict_set(>fc->metadata, "spherical", buffer, 0);
>> +}
>> +av_free(buffer);
>> }
>> return 0;
>> }
>> --
>> 2.6.3
>> 
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Re: [FFmpeg-devel] [PATCH] Add support for spherical uuid in mov

[Neil Birkbeck]

If you use "spherical-video" and put it in the stream's metadata, it
will more naturally agree with location in stream-level tag in mkv:
https://github.com/google/spatial-media/blob/master/docs/spherical-video-rfc.md

On Wed, Apr 20, 2016 at 6:24 PM, Colin McFadden  wrote:
> ---
>  libavformat/mov.c | 26 ++
>  1 file changed, 26 insertions(+)
>
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 47af98c..2223c81 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -3912,6 +3912,11 @@ static int mov_read_uuid(MOVContext *c, AVIOContext 
> *pb, MOVAtom atom)
>  0xbe, 0x7a, 0xcf, 0xcb, 0x97, 0xa9, 0x42, 0xe8,
>  0x9c, 0x71, 0x99, 0x94, 0x91, 0xe3, 0xaf, 0xac
>  };
> + static const uint8_t uuid_spherical[] = {
> +0xFF, 0xCC, 0x82, 0x63, 0xF8, 0x55, 0x4A, 0x93,
> +0x88, 0x14, 0x58, 0x7A, 0x02, 0x52, 0x1F, 0xDD
> +};
> +
>
>  if (atom.size < sizeof(uuid) || atom.size == INT64_MAX)
>  return AVERROR_INVALIDDATA;
> @@ -3987,6 +3992,27 @@ static int mov_read_uuid(MOVContext *c, AVIOContext 
> *pb, MOVAtom atom)
>  av_dict_set(>fc->metadata, "xmp", buffer, 0);
>  }
>  av_free(buffer);
> +} else if (!memcmp(uuid, uuid_spherical, sizeof(uuid))) {
> +uint8_t *buffer;
> +size_t len = atom.size - sizeof(uuid);
> +
> +buffer = av_mallocz(len + 1);
> +if (!buffer) {
> +return AVERROR(ENOMEM);
> +}
> +ret = avio_read(pb, buffer, len);
> +if (ret < 0) {
> +av_free(buffer);
> +return ret;
> +} else if (ret != len) {
> +av_free(buffer);
> +return AVERROR_INVALIDDATA;
> +}
> +if (c->export_all) {
> +buffer[len] = '\0';
> +av_dict_set(>fc->metadata, "spherical", buffer, 0);
> +}
> +av_free(buffer);
>  }
>  return 0;
>  }
> --
> 2.6.3
>
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