[FFmpeg-devel] [PATCH] avformat/isom: allow ISO 639 codes for mov

[Baptiste Coudurier]

Hi Yongle, I hope you are doing well

> On Jul 6, 2020, at 11:04 AM, Yongle Lin <yongle.lin.94 at gmail.com> wrote:
> 
> On Fri, Jun 19, 2020 at 5:11 PM Yongle Lin <yongle.lin.94 at gmail.com <mailto:yongle.lin.94 at gmail.com>> wrote:
> 
>> Allow ISO 639 language codes for text tracks in mov format when
>> strictness is set to experimental
>> ---
>> libavformat/isom.c             | 9 +++++++--
>> libavformat/isom.h             | 2 +-
>> libavformat/movenc.c           | 6 +++---
>> tests/fate/mov.mak             | 3 +++
>> tests/ref/fate/mov-iso639-lang | 4 ++++
>> 5 files changed, 18 insertions(+), 6 deletions(-)
>> create mode 100644 tests/ref/fate/mov-iso639-lang
>> 
>> diff --git a/libavformat/isom.c b/libavformat/isom.c
>> index 44c7b13038..de20ea8d8b 100644
>> --- a/libavformat/isom.c
>> +++ b/libavformat/isom.c
>> @@ -416,7 +416,7 @@ static const char mov_mdhd_language_map[][4] = {
>>     "cat", "lat", "que", "grn", "aym", "tat", "uig", "dzo", "jav"
>> };
>> 
>> -int ff_mov_iso639_to_lang(const char lang[4], int mp4)
>> +int ff_mov_iso639_to_lang(const char lang[4], int mp4, int
>> strict_std_compliance)
>> {
>>     int i, code = 0;
>> 
>> @@ -426,8 +426,13 @@ int ff_mov_iso639_to_lang(const char lang[4], int mp4)
>>             return i;
>>     }
>>     /* XXX:can we do that in mov too? */
>> -    if (!mp4)
>> +    if (!mp4 && (strict_std_compliance != FF_COMPLIANCE_EXPERIMENTAL ||
>> !strcmp(lang, "und"))) {
>> +        if (strcmp(lang, "und"))
>> +            av_log(NULL, AV_LOG_WARNING, "Non macintosh language is
>> discarded for mov\n");
>>         return -1;
>> +    }
>> +    if (!mp4)
>> +        av_log(NULL, AV_LOG_WARNING, "Experimental behavior: enable iso
>> 639 language in mov\n");
>>     /* handle undefined as such */
>>     if (lang[0] == '\0')
>>         lang = "und";
>> diff --git a/libavformat/isom.h b/libavformat/isom.h
>> index 41a9c64c11..9d018ebf1f 100644
>> --- a/libavformat/isom.h
>> +++ b/libavformat/isom.h
>> @@ -43,7 +43,7 @@ extern const AVCodecTag ff_codec_movaudio_tags[];
>> extern const AVCodecTag ff_codec_movsubtitle_tags[];
>> extern const AVCodecTag ff_codec_movdata_tags[];
>> 
>> -int ff_mov_iso639_to_lang(const char lang[4], int mp4);
>> +int ff_mov_iso639_to_lang(const char lang[4], int mp4, int
>> strict_std_compliance);
>> int ff_mov_lang_to_iso639(unsigned code, char to[4]);
>> 
>> struct AVAESCTR;
>> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
>> index 520aaafb74..4d7a98245e 100644
>> --- a/libavformat/movenc.c
>> +++ b/libavformat/movenc.c
>> @@ -3429,7 +3429,7 @@ static int mov_write_string_data_tag(AVIOContext
>> *pb, const char *data, int lang
>>         return size;
>>     } else {
>>         if (!lang)
>> -            lang = ff_mov_iso639_to_lang("und", 1);
>> +            lang = ff_mov_iso639_to_lang("und", 1, FF_COMPLIANCE_NORMAL);
>>         avio_wb16(pb, strlen(data)); /* string length */
>>         avio_wb16(pb, lang);
>>         avio_write(pb, data, strlen(data));
>> @@ -3468,7 +3468,7 @@ static AVDictionaryEntry
>> *get_metadata_lang(AVFormatContext *s,
>>     while ((t2 = av_dict_get(s->metadata, tag2, t2,
>> AV_DICT_IGNORE_SUFFIX))) {
>>         len2 = strlen(t2->key);
>>         if (len2 == len + 4 && !strcmp(t->value, t2->value)
>> -            && (l = ff_mov_iso639_to_lang(&t2->key[len2 - 3], 1)) >= 0) {
>> +            && (l = ff_mov_iso639_to_lang(&t2->key[len2 - 3], 1,
>> s->strict_std_compliance)) >= 0) {
>>             *lang = l;
>>             return t;
>>         }
>> @@ -6445,7 +6445,7 @@ static int mov_init(AVFormatContext *s)
>> 
>>         track->st  = st;
>>         track->par = st->codecpar;
>> -        track->language = ff_mov_iso639_to_lang(lang?lang->value:"und",
>> mov->mode!=MODE_MOV);
>> +        track->language = ff_mov_iso639_to_lang(lang?lang->value:"und",
>> mov->mode!=MODE_MOV, s->strict_std_compliance);
>>         if (track->language < 0)
>>             track->language = 32767;  // Unspecified Macintosh language
>> code
>>         track->mode = mov->mode;
>> diff --git a/tests/fate/mov.mak b/tests/fate/mov.mak
>> index 7a721d7c95..a85cc1a07d 100644
>> --- a/tests/fate/mov.mak
>> +++ b/tests/fate/mov.mak
>> @@ -29,6 +29,7 @@ FATE_MOV_FFPROBE = fate-mov-neg-firstpts-discard \
>>                    fate-mov-guess-delay-2 \
>>                    fate-mov-guess-delay-3 \
>>                    fate-mov-mp4-with-mov-in24-ver \
>> +                   fate-mov-iso639-lang \
>> 
>> FATE_MOV_FASTSTART = fate-mov-faststart-4gb-overflow \
>> 
>> @@ -124,3 +125,5 @@ fate-mov-faststart-4gb-overflow: CMP = oneline
>> fate-mov-faststart-4gb-overflow: REF = bc875921f151871e787c4b4023269b29
>> 
>> fate-mov-mp4-with-mov-in24-ver: CMD = run ffprobe$(PROGSSUF)$(EXESUF)
>> -show_entries stream=codec_name -select_streams 1
>> $(TARGET_SAMPLES)/mov/mp4-with-mov-in24-ver.mp4
>> +
>> +fate-mov-iso639-lang: CMD = ffmpeg$(PROGSSUF)$(EXESUF) -f lavfi -i
>> sine=frequency=1000:duration=15 -strict experimental -metadata:s:a:0
>> language=deu -y $(TARGET_PATH)/metadata.mov; run ffprobe -show_entries
>> stream=index:stream_tags=language $(TARGET_PATH)/metadata.mov; rm
>> metadata.mov
>> diff --git a/tests/ref/fate/mov-iso639-lang
>> b/tests/ref/fate/mov-iso639-lang
>> new file mode 100644
>> index 0000000000..6d1f61169d
>> --- /dev/null
>> +++ b/tests/ref/fate/mov-iso639-lang
>> @@ -0,0 +1,4 @@
>> +[STREAM]
>> +index=0
>> +TAG:language=deu
>> +[/STREAM]
>> --
>> 2.27.0.111.gc72c7da667-goog
>> 
>> Dear FFmpeg Developers,
> 
> Could you please review this patch when you have time. Thanks.
> 
> Best,
> Yongle


Is it allowed by an official spec ? What would be the reason to use these codes in mov ?

Thanks a lot! 

— 
Baptiste