Video quality lost when converting from .ogg to .mp4

[William Metcalf]

Thank you for the tip.  I was able to get a better quality video by 
changing the bit rate property of the video encoder module from its 
default 300 kbps to more closely match the bit rate of the .ogg file I 
am converting from.

On 6/6/2011 1:03 PM, Trever Fischer wrote:
> On Monday, June 06, 2011 10:46:55 AM William Metcalf wrote:
>> Hello all,
>>
>> I have written a gstreamer C application to convert a .ogg to .mp4
>> file.  The application is successful at converting the video and audio,
>> but the video produced after the conversion is of much lower quality
>> than the original video ( the audio converts with basically no loss I
>> can see).  I figure that some loss in video is to be expected, but I was
>> wondering what gstreamer modules might be good for helping lower the
>> loss in video quality.  Below is a snippet of my code that shows the
>> pipeline I used to convert the file.
> Converting from a lossy format to a lossy format almost always causes a
> reduction in quality. No real way to avoid that.
>> Thank you in advance for your help.
>>
>> int main (int argc, char *argv[])
>> {
>>       gst_init(&argc,&argv);
>>
>>       AV = 0;
>>
>>       loop = g_main_loop_new(NULL, FALSE);
>>
>>       /* Create elements */
>>       pipeline            = gst_pipeline_new("audio-player");
>>
>>       /* Element for reading in a file */
>>       source                = gst_element_factory_make("filesrc",
>> "file-source");
>>
>>       /* OGG elements */
>>       oggdemuxer            = gst_element_factory_make("oggdemux",
>> "ogg-demuxer");
>>       vorbis_decoder        = gst_element_factory_make("vorbisdec",
>> "vorbis-decoder");
>>       theora_decoder        = gst_element_factory_make("theoradec",
>> "theora-decoder");
>>
>>       /* MP4 elements */
>>       audio_encoder        = gst_element_factory_make("faac",
>> "aac-encoder"); video_encoder        =
>> gst_element_factory_make("ffenc_mpeg4", "avc-encoder");
>>       mp4_muxer            = gst_element_factory_make("qtmux", "mp4-muxer");
>>
>>       /* Audio/Video elements */
>>       video_converter        =
>> gst_element_factory_make("ffmpegcolorspace", "video-converter");
>>       videosink            = gst_element_factory_make("autovideosink",
>> "video-sink");
>>       video_scale            = gst_element_factory_make("videoscale",
>> "video-scale");
>>       video_rate            = gst_element_factory_make("videorate",
>> "video-rate");
>>       audio_resample        = gst_element_factory_make("audioresample",
>> "audio-resample");
>>       audio_rate            = gst_element_factory_make("audiorate",
>> "audio-rate");
>>       audiosink            = gst_element_factory_make("autoaudiosink",
>> "audio-sink");
>>       audio_converter        = gst_element_factory_make("audioconvert",
>> "audio-converter");
>>
>>       /* Queues */
>>       video_queue            = gst_element_factory_make("queue",
>> "video-queue");
>>       audio_queue            = gst_element_factory_make("queue",
>> "audio-queue");
>>       video_out_queue        = gst_element_factory_make("queue",
>> "video-out-queue");
>>       audio_out_queue        = gst_element_factory_make("queue",
>> "audio-out-queue");
>>
>>       /* Element to write to the file */
>>       filesink                = gst_element_factory_make("filesink",
>> "file-sink");
>>
>>       /* Make sure we were able to create all of the elements*/
>>       if(!pipeline || !source || !oggdemuxer || !vorbis_decoder ||
>> !theora_decoder || !audio_encoder || !video_encoder || !mp4_muxer ||
>> !audio_converter || !video_converter || !audio_resample || !audio_rate
>>
>> || !videosink || !audiosink || !video_queue || !audio_queue ||
>>
>> !video_out_queue || !audio_out_queue || !video_scale || !video_rate ||
>> !filesink )
>>       {
>>           g_printerr("One ore more elements could not be created.
>> Exiting.\n");
>>           return -1;
>>       }
>>
>>       /* Input file */
>>       g_object_set(G_OBJECT(source), "location", "c:\\video(1080p).ogg",
>> NULL);
>>       g_object_set(G_OBJECT(filesink), "location",
>> "c:\\Encoder_Output\\video(encoded from ogg).mp4", NULL);
>>
>>       /* Add a message handler from pipeline bus */
>>       bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline));
>>       gst_bus_add_watch(bus, bus_call, loop);
>>       gst_object_unref(bus);
>>
>>       /* add elements to the pipeline */
>>       gst_bin_add_many(GST_BIN(pipeline), source, oggdemuxer,
>> video_queue, theora_decoder, video_converter, video_scale, video_rate,
>> video_encoder, video_out_queue, audio_queue, vorbis_decoder,
>> audio_converter, audio_resample, audio_rate, audio_encoder,
>> audio_out_queue, mp4_muxer, filesink, NULL);
>>
>>       /* link the elements together */
>>       res = gst_element_link(source, oggdemuxer);
>>       if(!res)
>>       {
>>           g_printerr("There was a problem linking filesrc to oggdemux.\n");
>>           return 1;
>>       }
>>
>>       /* video_queue ->  theoradec ->  ffmpegcolorspace ->  ffenc_mpeg4 ->
>> video_out_queue ~>  qtmux */
>>       res = gst_element_link_many(video_queue, theora_decoder,
>> video_converter, video_scale, video_rate, video_encoder,
>> video_out_queue, NULL);
>>       if(!res)
>>       {
>>           g_printerr("There was a problem linking video elements.\n");
>>           return 1;
>>       }
>>       //link_video_caps(video_scale, video_encoder, 854, 480, 25, 1);
>>
>>       /* queue_audio ->  vorbisdec ->  audioconvert ->  faac ->
>> audio_out_queue ~>  qtmux */
>>       res = gst_element_link_many(audio_queue, vorbis_decoder,
>> audio_converter, audio_resample, audio_rate, audio_encoder,
>> audio_out_queue, NULL);
>>       if(!res)
>>       {
>>           g_printerr("There was a problem linking the audio elements.\n");
>>           return 1;
>>       }
>>       g_signal_connect(oggdemuxer, "pad-added", G_CALLBACK(on_pad_added),
>> NULL);
>>
>>       /* qtmux ->  filesink */
>>       res = gst_element_link(mp4_muxer, filesink);
>>       if(!res)
>>       {
>>           g_printerr("There was a problem linking qtmux to filesink.\n");
>>           return 1;
>>       }
>>
>>       link_video_to_multiplexer(video_out_queue, mp4_muxer);
>>       link_audio_to_multiplexer(audio_out_queue, mp4_muxer);
>>
>>
>>       /* Set the pipeline stat to play and start the main loop*/
>>       g_print("Starting the pipeline\n");
>>       gst_element_set_state(pipeline, GST_STATE_PLAYING);
>>       g_main_loop_run(loop);
>>
>>       /* We are done now, do a little bit of cleaning up */
>>       g_print("Stopping the pipeline.\n");
>>       gst_element_set_state(pipeline, GST_STATE_NULL);
>>       gst_object_unref(GST_OBJECT(pipeline));
>>
>>       return 0;
>> }
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>> gstreamer-devel at lists.freedesktop.org
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