[FFmpeg-devel] [PATCH 2/2] Encoding of styles - Bold, Italic, Underlined for timed-text subttiles
Niklesh Lalwani
niklesh.lalwani at iitb.ac.in
Fri Jun 12 10:05:05 CEST 2015
Yes, the patch is for single style record only. I'll work on multiple
style records now.
Thanks,
Niklesh
On 6/12/15, Philip Langdale <philipl at overt.org> wrote:
> On Thu, 11 Jun 2015 10:18:53 +0530
> Niklesh Lalwani <niklesh.lalwani at iitb.ac.in> wrote:
>
>> From: Niklesh <niklesh.lalwani at iitb.ac.in>
>>
>> Encoding of bold, Italic, underlined styles for 3gpp timed text
>> subtitles. All the formatting information is appended into the buffer
>> after the text, unlike other encoders like srt, which can write out
>> styling information as it goes. Another tricky part is to take care
>> of the Endianness properly while writing into the buffer.
>>
>> Signed-off-by: Niklesh <niklesh.lalwani at iitb.ac.in>
>> ---
>> libavcodec/movtextenc.c | 104
>> +++++++++++++++++++++++++++++++++++------------- 1 file changed, 76
>> insertions(+), 28 deletions(-)
>>
>> diff --git a/libavcodec/movtextenc.c b/libavcodec/movtextenc.c
>> index 1b8f454..adbe19d 100644
>> --- a/libavcodec/movtextenc.c
>> +++ b/libavcodec/movtextenc.c
>> @@ -24,14 +24,27 @@
>> #include "libavutil/avassert.h"
>> #include "libavutil/avstring.h"
>> #include "libavutil/intreadwrite.h"
>> +#include "libavutil/common.h"
>> #include "ass_split.h"
>> #include "ass.h"
>>
>> +#define STYLE_FLAG_BOLD 1
>> +#define STYLE_FLAG_ITALIC 2
>> +#define STYLE_FLAG_UNDERLINE 4
>> +
>> typedef struct {
>> ASSSplitContext *ass_ctx;
>> - char buffer[2048];
>> - char *ptr;
>> - char *end;
>> + AVBPrint buffer;
>> + uint32_t tsmb_size;
>> + uint32_t tsmb_type;
>> + uint16_t style_entries;
>> + uint16_t style_start;
>> + uint16_t style_end;
>> + uint16_t style_fontID;
>> + uint8_t style_flag;
>> + uint8_t style_fontsize;
>> + uint32_t style_color;
>> + uint16_t text_pos;
>> } MovTextContext;
>>
>>
>> @@ -47,10 +60,10 @@ static av_cold int
>> mov_text_encode_init(AVCodecContext *avctx)
>> 0xFF, // int8_t vertical-justification 0x00, 0x00,
>> 0x00, 0x00, // uint8_t background-color-rgba[4] // BoxRecord {
>> - 0x00, 0x00, // int16_t top
>> - 0x00, 0x00, // int16_t left
>> - 0x00, 0x00, // int16_t bottom
>> - 0x00, 0x00, // int16_t right
>> + 0x00, 0x01, // int16_t top
>> + 0x00, 0x01, // int16_t left
>> + 0x00, 0x1E, // int16_t bottom
>> + 0x00, 0xC8, // int16_t right
>
> Leave this part out of this diff. We'll deal with sizing later.
>
>> // };
>> // StyleRecord {
>> 0x00, 0x00, // uint16_t startChar
>> @@ -79,32 +92,54 @@ static av_cold int
>> mov_text_encode_init(AVCodecContext *avctx) if (!avctx->extradata)
>> return AVERROR(ENOMEM);
>>
>> + av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
>> +
>> memcpy(avctx->extradata, text_sample_entry,
>> avctx->extradata_size);
>> s->ass_ctx = ff_ass_split(avctx->subtitle_header);
>> return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
>> }
>>
>> +static void mov_text_style_cb(void *priv, const char style, int
>> close) +{
>> + MovTextContext *s = priv;
>> + s->tsmb_type = MKTAG('s','t','y','l');
>
> You don't need to do this. Use a simple boolean flag to indicate if any
> styles were generated.
>
>> + if (!close) {
>> + s->style_start = AV_RB16(&s->text_pos);
>> + switch (style){
>> + case 'b':
>> + s->style_flag += STYLE_FLAG_BOLD;
>> + break;
>> + case 'i':
>> + s->style_flag += STYLE_FLAG_ITALIC;
>> + break;
>> + case 'u':
>> + s->style_flag += STYLE_FLAG_UNDERLINE;
>> + break;
>> + }
>> + } else {
>> + s->style_end = AV_RB16(&s->text_pos);
>> + }
>> +}
>
> You are only storing a single set of style properties. So if multiple
> styles are used in the original subtitles, only the last one will take
> effect. You need to build up an array of style entries.
>
>> static void mov_text_text_cb(void *priv, const char *text, int len)
>> {
>> MovTextContext *s = priv;
>> - av_assert0(s->end >= s->ptr);
>> - av_strlcpy(s->ptr, text, FFMIN(s->end - s->ptr, len + 1));
>> - s->ptr += FFMIN(s->end - s->ptr, len);
>> + av_bprint_append_data(&s->buffer, text, len);
>> + s->text_pos += len;
>> }
>>
>> static void mov_text_new_line_cb(void *priv, int forced)
>> {
>> MovTextContext *s = priv;
>> - av_assert0(s->end >= s->ptr);
>> - av_strlcpy(s->ptr, "\n", FFMIN(s->end - s->ptr, 2));
>> - if (s->end > s->ptr)
>> - s->ptr++;
>> + av_bprint_append_data(&s->buffer, "\n", 2);
>> + s->text_pos += 2;
>> }
>>
>> static const ASSCodesCallbacks mov_text_callbacks = {
>> .text = mov_text_text_cb,
>> .new_line = mov_text_new_line_cb,
>> + .style = mov_text_style_cb,
>> };
>>
>> static int mov_text_encode_frame(AVCodecContext *avctx, unsigned
>> char *buf, @@ -112,10 +147,9 @@ static int
>> mov_text_encode_frame(AVCodecContext *avctx, unsigned char *buf, {
>> MovTextContext *s = avctx->priv_data;
>> ASSDialog *dialog;
>> - int i, len, num;
>> + int i, num;
>>
>> - s->ptr = s->buffer;
>> - s->end = s->ptr + sizeof(s->buffer);
>> + av_bprint_clear(&s->buffer);
>>
>> for (i = 0; i < sub->num_rects; i++) {
>>
>> @@ -123,33 +157,47 @@ static int mov_text_encode_frame(AVCodecContext
>> *avctx, unsigned char *buf, av_log(avctx, AV_LOG_ERROR, "Only
>> SUBTITLE_ASS type supported.\n"); return AVERROR(ENOSYS);
>> }
>> + s->text_pos = 0;
>>
>> dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass,
>> 0, &num); for (; dialog && num--; dialog++) {
>> ff_ass_split_override_codes(&mov_text_callbacks, s,
>> dialog->text); }
>> + if (s->tsmb_type == MKTAG('s','t','y','l') && s->style_end) {
>> + s->tsmb_size = MKTAG(0x00, 0x00, 0x00, 0x16);
>
> This can't be hard-coded, it will vary with the number of styles.
>
>> + s->style_entries = 0x00 | 0x01<<8;
>> + s->style_fontID = 0x00 | 0x01<<8;
>> + s->style_fontsize = 0x12;
>> + s->style_color = MKTAG(0xFF, 0xFF, 0xFF, 0xFF);
>> + av_bprint_append_data(&s->buffer, &s->tsmb_size, 4);
>> + av_bprint_append_data(&s->buffer, &s->tsmb_type, 4);
>> + av_bprint_append_data(&s->buffer, &s->style_entries, 2);
>> + av_bprint_append_data(&s->buffer, &s->style_start, 2);
>> + av_bprint_append_data(&s->buffer, &s->style_end, 2);
>> + av_bprint_append_data(&s->buffer, &s->style_fontID, 2);
>> + av_bprint_append_data(&s->buffer, &s->style_flag, 1);
>> + av_bprint_append_data(&s->buffer, &s->style_fontsize, 1);
>> + av_bprint_append_data(&s->buffer, &s->style_color, 4);
>> + }
>> }
>
> As above, this all assumes a single style.
>
>> - if (s->ptr == s->buffer)
>> - return 0;
>> -
>> - AV_WB16(buf, strlen(s->buffer));
>> + AV_WB16(buf, s->text_pos);
>> buf += 2;
>>
>> - len = av_strlcpy(buf, s->buffer, bufsize - 2);
>> -
>> - if (len > bufsize-3) {
>> - av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS
>> event.\n");
>> - return AVERROR(EINVAL);
>> - }
>> + if (!av_bprint_is_complete(&s->buffer))
>> + return AVERROR(ENOMEM);
>> + if (!s->buffer.len)
>> + return 0;
>>
>> - return len + 2;
>> + memcpy(buf, s->buffer.str, s->buffer.len);
>> + return s->buffer.len + 2;
>
> I would clear the bprint at the end so that it's not taking up memory
> after it's no longer of use.
>
>> }
>>
>> static int mov_text_encode_close(AVCodecContext *avctx)
>> {
>> MovTextContext *s = avctx->priv_data;
>> ff_ass_split_free(s->ass_ctx);
>> + av_bprint_finalize(&s->buffer, NULL);
>> return 0;
>> }
>>
>
>
>
>
> --phil
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